How do you calculate heart rate zones?

Multiply your maximum heart rate by the zone percentage. Zone 2 = 60–70% of MHR. Zone 4 = 80–90%. For a more accurate calculation, use the Karvonen formula: Target HR = Resting HR + (Zone % × (Max HR − Resting HR)). This accounts for your fitness level via resting heart rate.

What heart rate zone is best for fat burning?

Zone 2 (60–70% of max heart rate) burns the highest proportion of calories from fat. However, total calorie burn is lower than higher zones. For weight loss, total caloric deficit matters more than fat percentage. That said, Zone 2 training builds fat oxidation capacity that improves your ability to use fat as fuel at all intensities.

How do I find my maximum heart rate?

Estimate: use 208 − (0.7 × Age) for a reasonably accurate prediction. To test it directly: after thorough warm-up, run or cycle at maximal effort for 3–5 minutes — your peak HR near the end is close to your MHR. Field tests should only be done if you're healthy and ideally supervised. Actual MHR can vary ±10–15 bpm from formula estimates.

Why do professional athletes train mostly in Zone 2?

The 80/20 principle (polarized training) shows elite endurance athletes spend approximately 80% of training volume at low intensity (Zone 1–2) and 20% at high intensity (Zone 4–5), with very little in Zone 3. Zone 2 builds the aerobic base without generating excessive fatigue, allowing high-quality hard sessions to be repeated more frequently.

How Heart Rate Zones Work: Training Zones Explained with Formulas

Understand the 5 heart rate training zones, how to calculate your max heart rate, and how each zone benefits different fitness goals — from fat burning to VO2 max improvement.

Related Calculators

AP Macroeconomics Score Calculator
Estimate an AP Macroeconomics composite and AP score from MCQ and free-response performance.
Target Heart Rate Calculator
Calculate your target heart rate training zone from your age.
Therapy Productivity Calculator
Calculate your therapy productivity percentage — billable minutes over paid minutes.
Macro Calculator
Split a daily calorie target into protein, carbohydrate and fat grams using editable percentage targets.
Productivity Calculator
Calculate labor productivity — output per hour worked — and efficiency against a target.
Heart Rate Zone Calculator
Estimate training heart-rate zones from age and resting heart rate using the Karvonen heart-rate-reserve method.

What Are Heart Rate Training Zones?

Heart rate zones are ranges of heart rate expressed as percentages of your maximum heart rate (MHR). Training in different zones produces different physiological adaptations — from efficient fat burning to high-intensity lactate threshold improvements.

Step 1: Calculate Your Maximum Heart Rate

Traditional formula (Fox, 1971): MHR = 220 − Age

More accurate formula (Tanaka, 2001): MHR = 208 − (0.7 × Age)

Age	220−Age	Tanaka (208−0.7×Age)
25	195	191
35	185	184
45	175	177
55	165	170
65	155	163

The Tanaka formula is considered more accurate across age groups, particularly for older adults. However, actual MHR varies by ±10–15 bpm between individuals — a field test (supervised) gives the most accurate individual MHR.

The 5 Heart Rate Zones

Using MHR = 180 (example):

Zone	% of MHR	Heart Rate	Benefit
Zone 1 (Recovery)	50–60%	90–108	Active recovery, gentle circulation
Zone 2 (Aerobic Base)	60–70%	108–126	Fat oxidation, aerobic base building
Zone 3 (Aerobic)	70–80%	126–144	Cardiovascular fitness, improves aerobic capacity
Zone 4 (Threshold)	80–90%	144–162	Lactate threshold improvement, race pace
Zone 5 (Max)	90–100%	162–180	VO2 max, neuromuscular power, sprint capacity

Zone 2: The Endurance Foundation

Zone 2 (60–70% MHR) is where you can sustain effort for long periods while primarily burning fat. It's the zone professional endurance athletes spend 80% of their training time in.

Benefits of Zone 2 training: - Builds mitochondrial density in muscle cells - Maximizes fat oxidation efficiency - Low injury and recovery demand - Creates aerobic base that supports all other zones

Practical test: You can hold a conversation in Zone 2 without gasping. If you can't speak in sentences, you're in Zone 3+.

Zone 4: Lactate Threshold

Your lactate threshold (LT) is the intensity at which blood lactate begins accumulating faster than it's cleared — corresponding roughly to Zone 4. Training at and just below LT improves your ability to sustain hard efforts.

Why it matters: Lactate threshold pace determines race performance for events from 5K to half marathon. Improving LT allows you to race harder before glycolysis overwhelms aerobic metabolism.

Zone 5: VO2 Max Training

Short, high-intensity intervals in Zone 5 improve VO2 max — your maximum oxygen uptake capacity. This is the ceiling of your aerobic potential.

Typical protocol: 3–5 minute intervals at 90–95% MHR, 4–8 repetitions, twice per week.

Heart Rate Reserve Method (Karvonen)

A more personalized method using resting heart rate (RHR):

Zone Calculation: Target HR = RHR + (% of HRR) × (MHR − RHR)

Where HRR = Heart Rate Reserve = MHR − RHR

Example: MHR = 180, RHR = 55, Zone 3 (70–80% HRR): - HRR = 180 − 55 = 125 - Zone 3 low: 55 + 0.70 × 125 = 55 + 87.5 = 142.5 bpm - Zone 3 high: 55 + 0.80 × 125 = 55 + 100 = 155 bpm

The Karvonen method produces higher zone numbers than the simple percentage method, more closely approximating actual physiological zones for trained individuals with low RHR.

Related Guides

Frequently Asked Questions

How do you calculate heart rate zones?: Multiply your maximum heart rate by the zone percentage. Zone 2 = 60–70% of MHR. Zone 4 = 80–90%. For a more accurate calculation, use the Karvonen formula: Target HR = Resting HR + (Zone % × (Max HR − Resting HR)). This accounts for your fitness level via resting heart rate.
What heart rate zone is best for fat burning?: Zone 2 (60–70% of max heart rate) burns the highest proportion of calories from fat. However, total calorie burn is lower than higher zones. For weight loss, total caloric deficit matters more than fat percentage. That said, Zone 2 training builds fat oxidation capacity that improves your ability to use fat as fuel at all intensities.
How do I find my maximum heart rate?: Estimate: use 208 − (0.7 × Age) for a reasonably accurate prediction. To test it directly: after thorough warm-up, run or cycle at maximal effort for 3–5 minutes — your peak HR near the end is close to your MHR. Field tests should only be done if you're healthy and ideally supervised. Actual MHR can vary ±10–15 bpm from formula estimates.
Why do professional athletes train mostly in Zone 2?: The 80/20 principle (polarized training) shows elite endurance athletes spend approximately 80% of training volume at low intensity (Zone 1–2) and 20% at high intensity (Zone 4–5), with very little in Zone 3. Zone 2 builds the aerobic base without generating excessive fatigue, allowing high-quality hard sessions to be repeated more frequently.

Last updated 7/28/2026