Leap Year Calculator
Check whether any year is a leap year, using the exact Gregorian calendar rule — including the century-year exceptions most people don't know about.
Fill in the required fields to see your result.
Use this calculator on your website
Add this free Leap Year Calculator to your blog, article, or business website. Copy the embed code and publish it in minutes.
Perfect for blogs, WordPress, Webflow, and business websites.
1 means the year is a leap year (366 days, with February 29); 0 means it is a standard year (365 days).
Need a calculator like this?
Calciro can build a custom calculator around your formulas, pricing rules, or lead-generation process.
How the Leap Year Rule Works
A year is a leap year if it's divisible by 4, except century years (divisible by 100) — unless that century year is also divisible by 400. This is the exact rule used by the Gregorian calendar, and it's the reason 2000 was a leap year but 1900 was not.
How to Determine If a Year Is a Leap Year
A year qualifies as a leap year when it's divisible by 4 AND (not divisible by 100 OR divisible by 400).
Leap Year Calculator Formula
- Divisible by 4? If no, not a leap year.
- If yes, divisible by 100? If no, it is a leap year.
- If yes, divisible by 400? If yes, it is a leap year. If no, it is not.
Why Do Century Years Work Differently?
Without the century-year exception, the calendar would drift by about 3 days every 400 years relative to the solar year — the 100/400 rule keeps the Gregorian calendar closely aligned with Earth's actual orbital period.
Leap Year Examples
2028: Divisible by 4, not a century year — leap year.
1900: Divisible by 100 but not 400 — NOT a leap year.
2000: Divisible by 400 — leap year (the famous exception case).
Common Leap Year Misconceptions
Assuming every 4th year is automatically a leap year — century years are a genuine exception unless also divisible by 400. Assuming 1900 was a leap year just because it's divisible by 4 — it wasn't, precisely because of the century-year rule. Applying this rule to calendars other than the Gregorian calendar, which most of the world has used since 1582 (with varying adoption dates by country).
How to Use This Calculator
Enter any year.
Formula & Methodology
A year is a leap year if it's divisible by 4, EXCEPT century years (divisible by 100), UNLESS the year is also divisible by 400. This is the exact rule used by the Gregorian calendar.
Examples: 2024, 1900, and 2000
2024 is a leap year (divisible by 4, not a century year). 1900 is NOT a leap year (divisible by 100 but not 400). 2000 IS a leap year (divisible by 400).
Applies the Gregorian calendar rule only, used by most of the world since its adoption (1582 onward, with varying adoption dates by country). Does not account for other historical calendar systems.
Related Calculators
- Hebrew Birthday CalculatorCalculate Hebrew-calendar age and determine the anniversary month and day for a selected Hebrew year, including common Adar adjustments.
- Copart Fee CalculatorEstimate U.S. licensed-member Copart costs for a standard vehicle using current clean/non-clean and secured/unsecured fee schedules.
- Age CalculatorCalculate exact age in years and total days from a birth date.
- Clean Time CalculatorCalculate the number of days, months, and years since a sobriety or clean date.
- Audiobook Speed CalculatorCalculate how long an audiobook will take at a different playback speed and see how much listening time you can save.
Related Guides
- How Hebrew Birthdays WorkUnderstand sunset boundaries, Hebrew leap years, Adar I and Adar II, and why dedicated calendar conversion is necessary.
- Special-Purpose Calculators: Dates, Fees, and StandardsLearn why calendar conversion, changing fee schedules, and official scoring standards require different calculator designs.
- How Copart Buyer Fees WorkUnderstand Copart buyer-fee tiers, payment categories, title groups, virtual bid fees, and additional purchase costs.
- HYT (High Year of Tenure) Calculator GuideEstimate a projected HYT date from a service date and current authorized HYT limit.
- Air Force Promotion FAQAnswers to common questions about Senior Airman dates, BTZ eligibility, boards, Date of Rank, and official verification.
Frequently Asked Questions
- What is the leap year rule?
- A year is a leap year if it's divisible by 4, except century years (divisible by 100) — unless that century year is also divisible by 400. So 2000 was a leap year, but 1900 was not.
- Why do century years work differently?
- Without the century-year exception, the calendar would drift by about 3 days every 400 years relative to the solar year — the 100/400 rule keeps the Gregorian calendar closely aligned with Earth's orbit.
- How many days are in a leap year?
- 366 days — an extra day (February 29) is added compared to a standard 365-day year.
Last updated 7/12/2026