All Calculators

Browse free online calculators for construction, engineering, education, finance, fitness, automotive, dates, and more. Every calculator includes transparent formulas, worked examples, and clear explanations.

319 calculators

319 of 319 calculators

Health

Free health calculators with transparent formulas, editable assumptions and practical examples.

Blood Pressure Average Calculator

Calculate the arithmetic average of up to seven systolic and diastolic blood-pressure readings without diagnosing or classifying the result.

Caffeine Half-Life Calculator

Estimate how much caffeine may remain after a selected number of hours using an editable caffeine half-life.

Invisalign Price Calculator

Estimate Invisalign treatment cost, insurance contribution, down payment and an illustrative monthly payment from editable assumptions.

Refill Calculator

Estimate medication days of supply, expected run-out date and a reminder date from quantity, daily use and a planning buffer.

Construction

Free construction calculators with transparent formulas, editable assumptions and worked examples.

Concrete Driveway Cost Calculator

Estimate the cost of pouring a concrete driveway.

Soffit Calculator

Estimate soffit material needed from building dimensions.

CMU Block Calculator

Estimate how many standard 8x8x16 concrete masonry units (CMU) you need for a wall.

Loam Calculator

Calculate how much loam you need in cubic yards, tons, and cost.

Septic Tank Size Calculator

Estimate the minimum septic tank size based on the number of bedrooms.

Linear Feet to Square Feet Calculator

Convert linear feet to square feet using a known width.

Aluminum Coil Calculator

Calculate aluminum coil cross-sectional area, length, volume and estimated weight from width, thickness, density and either length or weight.

Asphalt Calculator

Calculate asphalt tonnage needed for a driveway or paving project.

Asphalt Calculator

Estimate asphalt volume, weight and tons required from project length, width, compacted thickness, density and waste allowance.

Baseboard Calculator

Estimate baseboard linear footage, stock pieces and material cost from room perimeter, excluded openings, waste and board length.

Concrete Block Calculator

Estimate the number of concrete blocks needed for a rectangular wall, including a waste allowance.

Drywall Calculator

Estimate drywall sheets, joint compound and screws from room perimeter, wall height, ceiling area, openings and waste allowance.

Fence Post Depth Calculator

Estimate fence post hole depth from post height, frost depth and gravel base.

Fill Dirt Calculator

Calculate how much fill dirt you need in cubic yards, tons, and cost.

Gravel Driveway Calculator

Estimate gravel driveway volume, weight and cost from dimensions, depth, material density, waste allowance and price per ton.

Hardie Siding Calculator

Estimate fiber cement siding area, squares and boards with waste allowance.

Linear Feet Calculator

Calculate total linear feet and inches from the number of equal-length pieces.

Metal Building Cost Calculator

Estimate metal building cost from floor area, shell cost, foundation, erection, interior build-out and contingency.

Paver Base Calculator

Estimate paver base and bedding sand volume, tons and material cost from project area, compacted depths and material densities.

Plywood Calculator

Calculate how many sheets of plywood or OSB you need for your project.

Pole Barn Cost Calculator

Estimate pole barn construction cost from building dimensions, cost per square foot, site work, doors, insulation and contingency.

Rafter Calculator

Calculate common rafter length from building width, roof pitch, and overhang.

Rebar Calculator

Estimate rebar line count, total length, stock bar quantity and material cost for a rectangular slab grid.

Retaining Wall Calculator

Estimate retaining wall block count, wall face area, base material and drainage stone from wall dimensions and block size.

River Rock Calculator

Calculate how much river rock you need in cubic yards, tons, and cost.

River Stone Calculator

Estimate river stone volume and weight from project length, width, depth and stone density, including a configurable waste allowance.

Roof Pitch Calculator

Calculate roof pitch ratio, slope percentage, angle and rafter length from rise, run and horizontal span.

Sand Calculator

Estimate sand volume in cubic feet and cubic yards, plus approximate weight in tons.

Sod Calculator

Calculate how many sod rolls or pallets you need for your lawn.

Stud Calculator

Calculate how many wall studs you need, including corners and openings.

Topsoil Calculator

Calculate how much topsoil you need in cubic yards, tons, and cost.

Wall Stud Calculator

Estimate wall studs from wall length, spacing, corners and openings.

Electrical & HVAC

Electrical and HVAC calculators for preliminary load, airflow, capacity and voltage-drop estimates.

Air Changes per Hour Calculator

Calculate air changes per hour from room volume and supplied or exhausted airflow.

Breaker Size Calculator

Estimate minimum circuit ampacity and breaker requirement from continuous and noncontinuous load currents using editable multipliers.

BTU Calculator

Estimate heating or cooling capacity from conditioned floor area and an editable BTU-per-square-foot design factor.

Duct CFM Calculator

Estimate airflow through a rectangular duct from duct dimensions and average air velocity.

Electrical Load Calculator

Estimate total electrical demand, apparent power and current from connected load, demand factor, voltage, phase factor and power factor.

Generator Sizing Calculator

Estimate generator running and starting capacity from total running watts, the largest additional surge load and an editable reserve margin.

Heat Pump Sizing Calculator

Estimate preliminary heat-pump capacity from floor area, design-load intensity and an editable sizing adjustment.

Mini Split Sizing Calculator

Estimate mini-split capacity from conditioned area, an editable BTU-per-square-foot factor and building adjustment.

Voltage Drop Calculator

Estimate conductor voltage drop and percentage voltage drop from current, one-way length, conductor resistance and circuit voltage.

Wire Size Calculator

Estimate the minimum conductor circular-mil area from current, distance, allowable voltage drop and conductor resistivity.

Business

Contractor rates, review ratings, financing, and other business planning calculators.

Seller Financing Calculator

Calculate the monthly payment for a seller-financed loan.

Share Incentive Plan Calculator

Calculate your tax and National Insurance saving from buying UK SIP Partnership Shares.

Google Review Calculator

Calculate how many new 5-star reviews you need to reach a target rating.

1099 Hourly Rate Calculator

Calculate the 1099 hourly rate you need to match a W-2 salary and benefits package.

1099 vs W-2 Calculator

Compare the total financial value of a W-2 job offer against 1099 contracting, including benefits, self-employment tax, and business costs.

AI Receptionist ROI Calculator

Estimate AI receptionist ROI from incoming calls, missed-call recovery, booking value, staff time savings and monthly software cost.

AI Voice Agent ROI Calculator

Estimate the financial return from an AI voice agent using call volume, handling rate, labor savings, recovered revenue and monthly platform cost.

ARR Calculator

Convert monthly recurring revenue to annual recurring revenue and estimate ARR growth from current and prior MRR.

Break-even Calculator

Calculate contribution margin, break-even units and break-even revenue from fixed costs, selling price and variable cost per unit.

Burn Rate Calculator

Calculate gross burn, net burn and monthly cash change from operating expenses and cash inflows.

CAC Calculator

Calculate customer acquisition cost from sales and marketing spend, new customers acquired and optional channel-level costs.

CD Calculator

Calculate the maturity balance and interest earned on a certificate of deposit using the deposit amount, APY, and term.

Churn Rate Calculator

Calculate customer churn, revenue churn and retention rates from beginning-of-period totals and losses during the period.

Consulting Rate Calculator

Calculate a sustainable consulting hourly or day rate from your income goal, overhead, and billable utilization.

EBITDA Calculator

Calculate EBITDA from net income by adding interest, taxes, depreciation and amortization.

Freelance Rate Calculator

Calculate a sustainable freelance hourly or day rate from your income goal, expenses, and non-billable time.

Gross Margin Calculator

Calculate gross profit, gross margin and cost-of-revenue percentage from revenue and direct cost of revenue.

LTV Calculator

Estimate customer lifetime value from average revenue per customer, gross margin and customer churn rate.

MRR Calculator

Calculate ending monthly recurring revenue and net new MRR from starting, new, expansion, contraction and churned MRR.

Reverse Sales Tax Calculator

Calculate the original price before sales tax and the tax amount included in a total purchase price.

Runway Calculator

Estimate business cash runway from available cash and monthly net burn.

Sales Commission Calculator

Calculate sales commission and net revenue after commission from eligible sales, commission rate, bonuses and deductions.

Work Hours Calculator

Calculate total hours worked minus unpaid break time.

Date & Time

Calculators for dates, durations, ages, and calendar math.

Hebrew Birthday Calculator

Calculate Hebrew-calendar age and determine the anniversary month and day for a selected Hebrew year, including common Adar adjustments.

Clean Time Calculator

Calculate the number of days, months, and years since a sobriety or clean date.

Mare Gestation Calculator

Estimate a mare's foaling date window from the breeding date.

Age Calculator

Calculate exact age in years and total days from a birth date.

Audiobook Speed Calculator

Calculate how long an audiobook will take at a different playback speed and see how much listening time you can save.

Days Until Calculator

Calculate the number of days until any future date.

Half Birthday Calculator

Calculate your next and previous half birthday, your age on that date, and how many days remain.

Leap Year Calculator

Check whether any year is a leap year using the official Gregorian calendar rule.

Automotive

Automotive calculators with transparent formulas, editable assumptions and practical examples.

Copart Fee Calculator

Estimate U.S. licensed-member Copart costs for a standard vehicle using current clean/non-clean and secured/unsecured fee schedules.

Vehicle Wrap Pricing Calculator

Estimate the cost range for a full or partial vehicle wrap.

0–60 MPH Calculator

Estimate a vehicle's 0–60 mph time from weight, horsepower and a traction or drivetrain efficiency factor.

1/4 Mile Calculator

Estimate quarter-mile elapsed time and trap speed from vehicle weight and horsepower using common empirical formulas.

Car Depreciation Calculator

Estimate your car's current value using straight-line depreciation.

Car Loan Calculator

Calculate your monthly car loan payment, total interest, and total cost.

Cost Per Mile Calculator

Calculate your true cost per mile driven, including fuel, insurance, maintenance, and loan payments.

Fuel Cost Calculator

Calculate the fuel cost for a trip.

Gear Ratio Speed Calculator

Estimate vehicle speed from engine RPM, transmission ratio, final-drive ratio and tire diameter.

Lease vs Buy Car Calculator

Compare estimated lease cost with financed purchase cost after depreciation, interest, fees, taxes and expected resale value.

Tacoma Tire Calculator

Compare Toyota Tacoma tire sizes, diameter, circumference, sidewall height and speedometer difference.

Toyota Payment Calculator

Estimate a Toyota vehicle loan payment from price, down payment, trade-in, tax, fees, APR and loan term.

Weight to Horsepower Ratio Calculator

Calculate vehicle weight-to-horsepower and horsepower-to-weight ratios from curb weight and engine horsepower.

Fitness

Training and performance calculators — pace, heart rate zones, and strength estimates.

Marine Corps PFT Calculator

Total three official USMC PFT event scores, classify the result, and apply the 2026 combat-arms 210-point requirement.

VDOT Running Calculator

Calculate your VDOT running fitness score from a recent race result, using the Jack Daniels formula.

Bowling Handicap Calculator

Calculate your bowling handicap from your average, basis score, and league percentage.

Productivity Calculator

Calculate labor productivity — output per hour worked — and efficiency against a target.

Running Record Calculator

Calculate reading accuracy, error rate, and self-correction rate from a running record.

Therapy Productivity Calculator

Calculate your therapy productivity percentage — billable minutes over paid minutes.

One Rep Max Calculator

Estimate your one-rep max (1RM) from a submaximal set, using the Epley formula.

Running Pace Calculator

Calculate your running pace per mile.

Smolov Jr Calculator

Generate a three-week Smolov Jr training table from a one-repetition maximum, training-max percentage, weekly increments and rounding interval.

Target Heart Rate Calculator

Calculate your target heart rate training zone from your age.

Home Improvement

Material and project-planning calculators for home improvement work.

Lawn Mowing Cost Calculator

Estimate what a professional lawn mowing service should cost.

Candle Wax Calculator

Calculate exactly how much wax and fragrance oil you need for your candle container.

Accent Wall Calculator

Estimate accent wall paint coverage, material quantity, paint cost, labor cost and total project cost from wall dimensions and editable assumptions.

ADU Calculator California

Build a California ADU planning estimate from floor area, construction rate, design and permit allowances, utility work, site work and contingency.

ADU ROI Calculator

Estimate accessory dwelling unit return on investment from project cost, expected rent, operating expenses, vacancy and estimated resale value added.

Air Conditioning Installation Cost Calculator

Estimate central air conditioning installation cost from equipment, labor and project extras.

Aluminum Fence Cost Calculator

Estimate the installed cost of an aluminum fence based on fence length and average price per linear foot.

Artificial Turf Cost Calculator

Estimate artificial turf installation cost from lawn area, material rate, labor rate, preparation cost and optional extras.

Carpet Cleaning Cost Calculator

Estimate carpet cleaning cost from cleaned area, price per square foot, room minimums, stairs and optional treatments.

Christmas Tree Light Calculator

Estimate Christmas tree light count and strand quantity from tree height, lights per foot and lights available on each strand.

Epoxy Calculator

Estimate epoxy volume from surface area, thickness, coats and waste.

Firewood Calculator

Calculate stacked firewood volume in cubic feet and full-cord equivalents.

Furnace and AC Replacement Cost Calculator

Estimate combined furnace and central AC replacement cost with labor and project adjustments.

Hardwood Floor Refinishing Cost Calculator

Estimate hardwood floor refinishing cost from floor area, sanding rate, finishing rate, repair allowance and moving costs.

Home Inspection Cost Calculator

Estimate home inspection cost from base fee, home size surcharge, age surcharge and optional specialty inspections.

Pond Liner Calculator

Calculate recommended rectangular pond liner length and width with depth and overlap.

Pressure Washing Estimate Calculator

Estimate pressure washing price from area, rate, minimum charge and add-ons.

Recessed Lighting Calculator

Estimate recessed light count and spacing from room dimensions and target coverage.

Square Footage Calculator

Calculate the square footage of a rectangular area.

TV Mounting Height Calculator

Estimate TV center and bottom mounting height from seated eye level, viewing distance, screen size and preferred viewing angle.

Education

Education calculators with transparent formulas, editable assumptions and practical examples.

AP Calculus AB Score Estimator

Estimate your AP Calculus AB score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP Calculus BC Score Estimator

Estimate your AP Calculus BC score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP Chemistry Score Estimator

Estimate your AP Chemistry score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP CSP Score Calculator

Estimate an AP Computer Science Principles composite from 70 MCQs and Create performance-task written-response performance.

AP English Language and Composition Score Estimator

Estimate your AP English Language and Composition score from your practice MCQ and essay scores — an independent, unofficial estimator.

AP European History Score Calculator

Estimate an AP European History composite and AP score from MCQ, SAQ, DBQ, and LEQ performance.

AP Human Geography Score Estimator

Estimate your AP Human Geography score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP Macroeconomics Score Calculator

Estimate an AP Macroeconomics composite and AP score from MCQ and free-response performance.

AP Microeconomics Score Calculator

Estimate an AP Microeconomics composite and AP score from MCQ and free-response performance.

AP Physics 1 (Algebra-Based) Score Estimator

Estimate your AP Physics 1 score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP Physics C Mechanics Score Calculator

Estimate an AP Physics C: Mechanics composite from 40 MCQs and four free-response question percentages.

AP Psychology Score Estimator

Estimate your AP Psychology score from your practice MCQ, AAQ, and EBQ raw scores — an independent, unofficial estimator.

AP Statistics Score Estimator

Estimate your AP Statistics score from your practice MCQ and FRQ raw scores — an independent, unofficial estimator.

AP United States History (APUSH) Score Estimator

Estimate your AP US History score from your practice MCQ, SAQ, DBQ, and LEQ scores — an independent, unofficial estimator.

AP World History: Modern Score Estimator

Estimate your AP World History: Modern score from your practice MCQ, SAQ, DBQ, and LEQ scores — an independent, unofficial estimator.

Grade Curve Calculator

Apply a flat-point curve to a test score.

Grading Bell Curve Calculator

Curve a raw score to a target class average and spread using z-score scaling.

Law School GPA Calculator

Calculate your new cumulative GPA after adding a new semester's grades.

IU GPA Calculator

Calculate your updated Indiana University cumulative GPA using the official IU grading scale.

Law School Scholarship Calculator

Calculate the total value of a law-school scholarship, net tuition, renewal-risk scenarios, and effective tuition discount.

Oakland University GPA Calculator

Estimate your Oakland University semester or cumulative GPA using OU's official 4.0 grade-point values.

2's Complement Calculator

Convert a signed decimal number to its two's complement unsigned decimal equivalent.

Water Potential Calculator

Calculate water potential and solute potential using the official AP Biology formula.

AP Calc Score Calculator

Estimate an AP Calculus composite score and projected 1–5 result from multiple-choice and free-response performance using clearly editable weighting assumptions.

AP Chem Exam Score Calculator

Estimate an AP Chemistry composite percentage from multiple-choice and free-response performance using editable section weights.

AP English Language Score Calculator

Estimate an AP English Language composite percentage and planning score from multiple-choice and essay performance with editable weights and thresholds.

AP World Calculator

Estimate an AP World History composite percentage from multiple-choice, short-answer, document-based and long-essay performance.

AP World Score Calculator

Convert an estimated AP World composite percentage into a planning score from 1 to 5 using editable score thresholds.

Arizona State University GPA Calculator

Estimate your Arizona State term and projected cumulative GPA using the university's published grade-point scale.

Auburn University GPA Calculator

Estimate your Auburn term and projected cumulative GPA using the university's grading scale.

Broward Grade Calculator

Estimate a weighted course grade using quarter grades, a midterm or semester assessment and a final exam with editable weights.

Class Rank Calculator

Estimate class rank, percentile and percentile-from-top using a student's rank and the total number of students in the class.

Clemson University GPA Calculator

Estimate your Clemson term and projected cumulative GPA using the university's grading scale.

College GPA Calculator

Calculate a college or university GPA using course grades and credit hours.

Cumulative GPA Calculator

Estimate your new cumulative GPA by combining your current record with a new semester or group of courses.

Cumulative GPA Calculator ASU

Estimate a new cumulative GPA from current GPA, completed credits and the grade points and credits from a new ASU term.

HCPSS Grade Calculator

Estimate an HCPSS-style semester course grade from two quarter grades and a final assessment using editable 40%, 40% and 20% weights.

High School GPA Calculator

Calculate your high school GPA on a standard 4.0 scale using letter grades and course credits.

Indiana University GPA Calculator

Estimate your Indiana University term and projected cumulative GPA using the university's grading scale.

Iowa State University GPA Calculator

Estimate your Iowa State term and projected cumulative GPA using the university's grading scale.

Law School Acceptance Calculator

Compare your LSAT and GPA with a target school's published 25th, 50th and 75th percentile figures using a transparent profile-position score.

Louisiana State University GPA Calculator

Estimate your LSU term and projected cumulative GPA using the university's grading scale.

LSAC GPA Calculator

Estimate your LSAC cumulative undergraduate GPA using the common LSAC grade-conversion values from A+ through F.

LSAT Score Calculator

Total your scored-section correct answers and calculate raw accuracy before checking the official conversion table for your exact test form.

Michigan State University GPA Calculator

Estimate your Michigan State term and projected cumulative GPA using the university's grading scale.

NC State University GPA Calculator

Estimate your NC State term and projected cumulative GPA using the university's grading scale.

Oregon State University GPA Calculator

Estimate your Oregon State term and projected cumulative GPA using the university's grading scale.

Penn State University GPA Calculator

Estimate your Penn State term and projected cumulative GPA using the university's published grade-point scale.

Punnett Square Calculator

Calculate AA, Aa and aa offspring probabilities from the probability that each parent passes a dominant allele.

Purdue University GPA Calculator

Estimate your Purdue University semester GPA and cumulative graduation index using Purdue's published grade weights.

Rutgers University GPA Calculator

Estimate your Rutgers term and projected cumulative GPA using the university's grading scale.

Semester GPA Calculator

Calculate your GPA for one semester or academic term using course grades and credit hours.

Texas A&M University GPA Calculator

Estimate your Texas A&M term and projected cumulative GPA using the university's published grade-point scale.

The Ohio State University GPA Calculator

Estimate your Ohio State term and projected cumulative GPA using the university's published grade-point scale.

The University of Texas at Austin GPA Calculator

Estimate your UT Austin term and projected cumulative GPA using the university's published grade-point scale.

University of Alabama GPA Calculator

Estimate your University of Alabama term and projected cumulative GPA using the university's grading scale.

University of Colorado Boulder GPA Calculator

Estimate your CU Boulder term and projected cumulative GPA using the university's grading scale.

University of Florida GPA Calculator

Estimate your University of Florida term and cumulative GPA using UF's published grade values and hundredths-place display rule.

University of Georgia GPA Calculator

Estimate your UGA term and projected cumulative GPA using the university's published grade-point scale.

University of Illinois Urbana-Champaign GPA Calculator

Estimate your UIUC term and projected cumulative GPA using the university's grading scale.

University of Kansas GPA Calculator

Estimate your University of Kansas term and projected cumulative GPA using the university's grading scale.

University of Kentucky GPA Calculator

Estimate your University of Kentucky term and projected cumulative GPA using the university's grading scale.

University of Maryland GPA Calculator

Estimate your University of Maryland term and projected cumulative GPA using the university's grading scale.

University of Michigan GPA Calculator

Estimate your Michigan term and projected cumulative GPA using the university's published grade-point scale.

University of Minnesota Twin Cities GPA Calculator

Estimate your University of Minnesota term and projected cumulative GPA using the university's published grade-point scale.

University of Missouri GPA Calculator

Estimate your Mizzou term and projected cumulative GPA using the university's grading scale.

University of South Carolina GPA Calculator

Estimate your South Carolina term and projected cumulative GPA using the university's grading scale.

University of Tennessee GPA Calculator

Estimate your University of Tennessee term and projected cumulative GPA using the university's grading scale.

University of Washington GPA Calculator

Estimate your University of Washington term and projected cumulative GPA using the university's grading scale.

University of Wisconsin–Madison GPA Calculator

Estimate your UW–Madison term and projected cumulative GPA using the university's published grade-point scale.

Unweighted GPA Calculator

Calculate an equal-weight unweighted GPA from eight letter grades on a standard 4.0 scale.

Virginia Tech GPA Calculator

Estimate your Virginia Tech term and projected cumulative GPA using the university's grading scale.

Weighted GPA Calculator

Calculate a weighted GPA by adding course-level points for honors, AP, IB, or advanced classes.

Landscaping

Free landscaping calculators for mulch, pine straw, gravel, soil, sand, compost, lawn projects, patios, retaining walls, and other outdoor improvements. Calculate materials, coverage, volume, and project costs quickly and accurately.

Pine Straw Calculator

Calculate how many pine straw bales you need based on area, bale coverage and extra material allowance.

Health & Fitness

Health & Fitness calculators with transparent formulas, editable assumptions and practical examples.

Body Surface Area Calculator

Estimate body surface area from height and weight using the Mosteller formula.

Calorie Deficit Calculator

Estimate a daily calorie target and theoretical weekly weight change from maintenance calories and an editable calorie deficit.

Heart Rate Zone Calculator

Estimate training heart-rate zones from age and resting heart rate using the Karvonen heart-rate-reserve method.

How Much Water Should I Drink on Creatine Calculator

Estimate a general daily fluid target from body weight, exercise duration, climate adjustment and creatine use assumptions.

Losertown Calculator

Project weekly body-weight change from current weight, calorie intake, age, height, sex and activity using a dynamic energy-balance estimate.

Macro Calculator

Split a daily calorie target into protein, carbohydrate and fat grams using editable percentage targets.

Protein Calculator

Estimate a daily protein intake range from body weight, activity level and goal using editable grams-per-kilogram assumptions.

VO2 Max Calculator

Estimate VO2 max using the Cooper 12-minute run formula from distance covered in meters.

Water Intake Calculator

Estimate a daily water-intake range from body weight using editable milliliters-per-kilogram assumptions.

Wilks Calculator

Calculate a Wilks score from body weight, total lifted weight and sex using the classic Wilks coefficient formula.

Math

Free math calculators with transparent formulas, editable assumptions and practical examples.

Exponential Growth Calculator

Calculate future value, total growth and doubling time from an initial amount, percentage growth rate and number of periods.

Fast Calculator

Perform a quick arithmetic calculation using two numbers and an operation code for addition, subtraction, multiplication or division.

Gematria Calculator

Calculate the gematria or isopsephy value of any word, name, or phrase using English, Hebrew, or Greek letter-value systems.

Percentage Calculator

Solve five common percentage problems, including percentage of a number, percent of a total, reverse percentage, and percent greater or less.

Percentage Change Calculator

Calculate directional percentage change between an old value and a new value.

Percentage Decrease Calculator

Calculate the absolute decrease and percentage decrease from an original value to a lower value.

Percentage Difference Calculator

Calculate the symmetric percentage difference between two nonnegative values.

Percentage Increase Calculator

Calculate the absolute increase and percentage increase from an original value to a higher value.

Racine Carrée Calculator

Calculate the principal square root of a nonnegative number with a transparent formula and worked examples.

Reverse Percentage Calculator

Find the original value before a discount, reduction, markup, tax, or percentage increase was applied.

What Percentage Is X of Y Calculator

Find what percentage one value represents of another value.

Military

Military pay, retirement, promotion, career, date, and service-related calculators.

USAF BTZ Calculator

Estimate your normal Senior Airman date, six-month-early BTZ sew-on date, and likely quarterly promotion window.

Air Force Retirement Calculator

Estimate your 20-year active-duty retirement eligibility date and retirement multiplier.

BAH Calculator

Compare an official monthly BAH rate with housing costs and calculate annual allowance.

BAS Calculator

Estimate 2026 monthly and annual BAS for enlisted members or officers.

Deployment Pay Calculator

Estimate total gross deployment compensation from entered monthly pay and allowance amounts.

Drill Pay Calculator (ANG/Reserve)

Estimate gross drill pay from monthly active-duty basic pay and paid drill periods.

HYT (High Year of Tenure) Calculator

Estimate a projected HYT date from a service date and current authorized HYT limit.

Leave Accrual Calculator

Project a military leave balance using the standard 2.5-day monthly accrual rate.

Military Pay Raise Calculator

Estimate new monthly and annual basic pay after a percentage raise.

Military Retirement Pay Calculator

Estimate gross monthly and annual military retired pay from a retired-pay base and longevity multiplier.

PCS Date Calculator

Estimate a departure date from a report-no-later-than date and authorized travel days.

Promotion Points Calculator

Add verified promotion-score components and compare the total with a cutoff score.

Time in Grade Calculator

Calculate time in grade from Date of Rank to an as-of date.

Time in Service Calculator

Calculate military time in service between two dates.

Engineering

Free engineering calculators with transparent formulas, editable assumptions and worked examples.

Boiler Feed Pump Calculator

Size a boiler feed pump's capacity from steam output and a safety factor.

Tank Volume Calculator

Calculate cylindrical tank volume in gallons from diameter and height measurements.

Friction Loss Calculator

Calculate pipe friction loss using the Hazen-Williams formula, standard for fire service and plumbing.

Amps to kW Calculator

Convert amps to kilowatts for single-phase and three-phase electrical loads.

Equivalent Nodal Loads Calculator

Calculate the consistent local nodal-force vector for a two-node Euler–Bernoulli beam under a linearly varying transverse load.

Bending Angle Calculator

Calculate sheet metal bend allowance from bend angle, inside radius, thickness, and K-factor.

Planar Density Calculator

Calculate planar atomic density from a two-dimensional repeating cell, shared atom counts, side lengths, and included angle.

Sky Background Electron Rate Calculator

Convert sky surface brightness and an electron-rate zero point into sky electrons per pixel, aperture background, and detector noise.

3 Phase Power Calculator

Calculate three-phase real power, apparent power and reactive power from line voltage, current and power factor.

Angle Iron Load Capacity Calculator

Estimate simply supported angle-iron bending capacity from section modulus, allowable bending stress, span and a user-entered stability reduction factor.

Annular Volume Calculator

Calculate annular cross-sectional area and volume between an outer diameter and inner diameter over a selected length.

Gas Spring Calculator

Estimate the gas-spring force needed to support a hinged lid from lid weight, center-of-gravity distance, mounting distance, angle and number of springs.

Line Pipe Weight Calculator

Estimate steel line-pipe weight from outside diameter, wall thickness, length and material density.

Link Seal Calculator

Estimate the annular gap, seal centerline circumference and approximate modular-link count for a pipe passing through a round opening.

Steam Turbine Real-World Efficiency Calculator

Calculate steam turbine isentropic efficiency, power output, and the estimated impact of pressure and temperature inconsistencies.

Watts to Amps Calculator

Convert watts to amps for DC, single-phase AC or three-phase AC circuits using voltage, power factor and efficiency.

Energy

Calculators for electricity, gas, tariffs, consumption, wholesale costs, and household energy bills.

Solar Panel Angle Calculator

Estimate a practical solar panel tilt angle from latitude and an optional seasonal adjustment for planning purposes.

Solar Panel Tilt Angle Calculator

Calculate annual, summer and winter solar panel tilt suggestions from latitude using transparent adjustable offsets.

Wholesale Electricity Cost Calculator

Estimate how much of a Great Britain household electricity bill comes from wholesale energy costs.

Gaming

Free gaming calculators with transparent formulas, editable assumptions and worked examples.

Kingshot Calculator

Estimate Kingshot research completion time after Academy speed bonuses, help reductions, and speedups.

Last War Research Calculator

Estimate Last War research time after research-speed bonuses, alliance help, and stored speedups.

MapleStory EXP Calculator

Calculate EXP remaining, kills or actions required, and estimated training time from your own MapleStory values.

MapleStory Liberation Calculator

Estimate weeks remaining for Genesis Weapon liberation from current Traces of Darkness and recurring weekly or monthly income.

MTG Land Calculator

Estimate a starting land count for 40, 60, or 100-card Magic decks and review approximate land-draw probabilities by turn.

OSRS Dry Calculator

Calculate your probability of still being dry (or having received a drop) at any Old School RuneScape drop rate and kill count.

Pokemon Shiny Probability Calculator

Calculate effective shiny odds, the chance of finding at least one shiny after repeated encounters, and attempts needed for common confidence levels.

ROTMG DPS Calculator

Estimate ROTMG weapon DPS from damage, projectiles, ATK, attack rate, target DEF, accuracy, and buffs.

Uma Musume Stamina Calculator

Compare effective stamina with a user-defined race target after distance, condition, aptitude, and recovery assumptions.

Anime Vanguards Calculator

Estimate Anime Vanguards unit damage per hit, attacks per second, DPS and total damage after upgrades, traits and external multipliers.

Arma Reforger Mortar Calculator

Estimate map bearing, horizontal range and mil-based angular correction between a mortar position and target coordinates in Arma Reforger.

Catch Rate Calculator

Estimate Pokémon capture chance from HP, species catch rate, Poké Ball modifier and status-condition modifier.

Dynasty Baseball Trade Calculator

Compare dynasty baseball trade packages from user-entered player and pick values, roster adjustments and league-specific premiums.

Elden Ring Weapon Calculator

Estimate an Elden Ring weapon's displayed attack rating from base attack, scaling coefficients, attribute saturation values and temporary modifiers.

Last War Event Calculator

Estimate event points from troops, research, building power, speedups and other point-generating actions.

Last War Resource Calculator

Total available Iron, Food and Gold, compare them with upgrade requirements and calculate shortages.

Last War Speedup Calculator

Combine speedup items, compare them with an adjusted timer and calculate the remaining time or surplus.

Last War Troop Training Calculator

Estimate adjusted troop-training time, speedup coverage, resource cost, power gain and event points.

MapleStory Cube Calculator

Estimate cube success probability, expected attempts and total cubing cost from a current success-rate assumption.

MapleStory Damage Calculator

Compare a baseline damage value with additive damage, boss damage, final damage and enemy defense assumptions.

MapleStory Hyper Stat Calculator

Calculate the Hyper Stat points needed to move a stat from one level to another.

OSRS Agility Calculator

Calculate Agility XP remaining, laps needed, estimated time, XP per hour, expected Marks of Grace, reward value, and net value.

OSRS Combat Calculator

Calculate your Old School RuneScape combat level from your Attack, Strength, Defence, Hitpoints, Ranged, Magic, and Prayer levels.

OSRS Combat Level Calculator

Calculate OSRS combat level from Attack, Strength, Defence, Hitpoints, Prayer, Ranged, and Magic.

OSRS Cooking Calculator

Calculate Cooking XP, successful cooks, raw food required, expected burns, cost, output value, time, and GP per XP.

OSRS Crafting Calculator

Estimate Crafting actions, materials, XP, time, cost, revenue, and net profit or loss for a manual training method.

OSRS DPS Calculator

Calculate manual-mode Old School RuneScape DPS for melee or ranged setups using attack rolls, defence rolls, max hit, weapon ticks, and hit chance.

OSRS Drop Rate Calculator

Calculate zero-drop, at-least-one, exactly-k, and target-confidence probabilities for independent OSRS drop rolls.

OSRS Firemaking Calculator

Calculate Firemaking XP remaining, logs or actions needed, supply cost, reward value, time, GP per XP, and XP per hour.

OSRS Fishing Calculator

Calculate Fishing XP remaining, catches needed, expected catch attempts, time, XP per hour, catch value, GP per hour, and total value.

OSRS Giants' Foundry Calculator

Estimate swords, Smithing XP, bars or items consumed, reputation, time, supply cost, rewards, and net value at Giants' Foundry.

OSRS Herblore Calculator

Calculate Herblore XP remaining, potions needed, herbs and secondary ingredients, time, cost, output value, and GP per XP.

OSRS Mahogany Homes Calculator

Calculate contracts, Construction XP, planks, steel bars, Carpenter points, time, cost, GP per XP, and reward progress.

OSRS Max Hit Calculator

Calculate a manual melee or ranged maximum hit from level, boost, prayer, style, void, equipment bonus, and damage multipliers.

OSRS Prayer Calculator

Calculate Prayer XP remaining, XP per offering, expected offerings, supply cost, GP per XP, and training time.

OSRS Runecrafting Calculator

Calculate Runecrafting XP remaining, essence and actions needed, runes produced, time, gross value, supply cost, profit, GP per hour, and GP per XP.

OSRS Skill Calculator

Calculate XP remaining, actions, materials, time, and cost for any OSRS skill using a manual training method.

OSRS ToA Loot Calculator

Calculate cumulative ToA purple chance, expected unique chests, target-item chance, expected value, raids required, and GP per hour.

OSRS XP Calculator

Calculate XP remaining to a target level, progress percentage, estimated time, actions, and projected XP.

Pokémon Type Coverage Calculator

Summarize a move set's type coverage from the number of defending types hit super effectively, neutrally, resisted or immune.

Tradeup Calculator

Estimate the expected value, profit and break-even probability of a game-item trade-up from input cost, outcome values and outcome probabilities.

UMA Deck Calculator

Estimate an Uma Musume support-deck balance score from card levels, friendship bonuses, race bonuses and training-effect values entered by the player.

Uma Musume Race Calculator

Estimate race HP from track distance, stamina, running-style coefficient and recovery skills.

Uma Musume Skill Point Calculator

Plan skill purchases using base costs, hint discounts, available points and reserved points.

Uma Musume Stat Calculator

Estimate final Speed, Stamina, Power, Guts and Wit from current stats and planned gains.

Uma Musume Training Calculator

Estimate stat gains from repeated training sessions with motivation and support-bonus multipliers.

Finance

Free finance calculators with transparent formulas, editable assumptions and worked examples.

ADU Financing Calculator

Estimate an ADU loan payment, total interest and required cash using project cost, down payment, annual interest rate, term and closing costs.

Aircraft Value Calculator

Estimate an aircraft's market value from an editable reference value, age depreciation, airframe time, engine reserve, condition and equipment adjustments.

Barista FIRE Calculator

Estimate the portfolio needed for Barista FIRE after part-time income covers part of annual retirement spending.

Bilt 2.0 Calculator

Estimate Bilt Cash coverage, rent-payment fees, annual rent points and approximate net reward value under editable Bilt 2.0 assumptions.

BRRRR Calculator

Estimate total project cost, refinance proceeds, cash left in a BRRRR deal, rental cash flow and cash-on-cash return.

Cap Rate Calculator

Calculate capitalization rate, net operating income and value at a target cap rate using property income and operating expenses.

Cash Flow Calculator

Estimate monthly and annual rental-property cash flow after vacancy, operating expenses, reserves and debt payments.

Chapter 13 Calculator

Estimate a preliminary monthly repayment budget from disposable income, plan length and selected priority or secured obligations without pretending to calculate a court-approved Chapter 13 plan.

Closing Cost Calculator

Estimate buyer cash needed at closing from down payment, lender fees, title charges, prepaid items, taxes and credits.

DSCR Calculator

Calculate debt service coverage ratio from gross operating income, vacancy, operating expenses and annual debt service.

GM Income Calculator

Convert hourly, weekly, biweekly, semimonthly or annual gross pay into comparable estimated monthly and annual income figures.

Guitar Center Trade-In Value Calculator

Estimate a music-gear trade-in offer from expected resale value, dealer margin, condition, demand and repair-cost assumptions.

HELOC Payment Calculator

Estimate interest-only and amortizing HELOC payments from the current balance, annual rate and repayment term.

House Flipping Profit Calculator

Estimate house-flipping profit, return on cost and break-even resale price from purchase, renovation, holding, financing and selling costs.

Indiana Income Calculator

Estimate 2026 Indiana state and county income tax from Indiana taxable income, county rate, credits and withholding.

LRP Calculator

Estimate Livestock Risk Protection insured weight, producer premium and a hypothetical indemnity from user-entered coverage and price values.

Mortgage Recast Calculator

Estimate a new monthly principal-and-interest payment after a mortgage recast using the remaining balance, lump-sum payment, interest rate and remaining term.

QQQI Dividend Calculator

Estimate QQQI share count and monthly or annual distribution income from an investment amount, share price and user-entered distribution yield.

Rent vs Sell Calculator

Compare an estimated multi-year outcome from renting a property versus selling now using rent, expenses, appreciation, selling costs and investment return assumptions.

Rental Property ROI Calculator

Estimate rental-property cash-on-cash return, total first-year ROI, cap rate and annual cash flow from income, expenses, financing and appreciation assumptions.

Retirement Savings Longevity Calculator

Estimate how long retirement savings may last using the starting balance, annual withdrawal, expected return and inflation assumptions.

Roth 401(k) Calculator

Estimate the future after-tax value of Roth 401(k) contributions using contribution amount, employer match, investment return, years and tax assumptions.

Roth or 401(k) Calculator

Compare simplified after-tax future values for Roth and traditional 401(k) contributions using current and retirement tax rates.

Seller Net Sheet Calculator

Estimate a home seller’s net proceeds after mortgage payoff, commissions, transfer taxes, concessions, repairs and other closing charges.

Velocity Banking Calculator

Estimate the potential interest and time effect of applying recurring extra cash flow to a mortgage or other amortizing debt.

Featured Calculator Hubs

Focused collections of related calculators, organized by topic.

OSRS Calculators

Old School RuneScape calculators for combat level, DPS, max hit, Prayer, XP, skills, Crafting, and drop-rate planning.

19 calculators

Landscaping Calculators

Free landscaping calculators for topsoil, mulch, gravel, river rock, sand, sod, pavers, pine straw, and other landscaping materials. Estimate quantities using transparent formulas and worked examples.

7 calculators

Percentage Calculators

Free percentage calculators for amounts, increase, decrease, change, difference, reverse percentages, and more.

7 calculators

GPA Calculators

Free GPA calculators for high school, college, weighted, unweighted, semester, and cumulative GPA.

6 calculators

Real Estate Investment Calculators

Real Estate Investment Calculators with visible formulas and user-controlled assumptions.

6 calculators

Gaming Progression Calculators

Gaming calculators for research timers, EXP, stamina benchmarks and DPS.

5 calculators

Free Online Calculators with Transparent Methods

This directory covers practical, academic, technical, financial, and everyday calculations — from construction materials and engineering formulas to AP exam scores, GPA, and fitness metrics.

Every calculator documents the formula or methodology behind its result, along with a worked example and any limitations, so you can see exactly how the number was reached rather than just trusting a black box.

Calculators are organized into categories and focused calculator hubs above, so related tools are easy to find. You can also browse individual category pages for a narrower view of any single topic.