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Heart Rate Zone Calculator

Calculate your heart rate training zones using the Karvonen formula. See 5 zones with personalized HR ranges for optimal training.

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Your Heart Rate Info

Heart Rate Zones (Karvonen)

Max HR

190 bpm

HR Reserve

125 bpm

Zone 1 - Recovery128 - 140 bpm
Very light effort, warm-up
Zone 2 - Fat Burn140 - 153 bpm
Light effort, fat burning
Zone 3 - Aerobic153 - 165 bpm
Moderate effort, endurance
Zone 4 - Threshold165 - 178 bpm
Hard effort, speed training
Zone 5 - Max178 - 190 bpm
Maximum effort, short bursts
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How to Use Heart Rate Zone Calculator

  1. 1

    Enter your age

    Your age is used to estimate your maximum heart rate (220 - age).

  2. 2

    Enter resting HR

    Measure your resting heart rate first thing in the morning for best accuracy.

  3. 3

    Optional: custom max HR

    If you know your actual max heart rate, enter it for more precise zones.

  4. 4

    View zones

    See five training zones with heart rate ranges and descriptions.

Frequently Asked Questions

The Karvonen formula calculates target heart rate as: Target HR = ((Max HR - Resting HR) * intensity%) + Resting HR. It's more accurate than simple percentage-of-max methods because it accounts for your resting heart rate.

Zone 1 (50-60%): Recovery/warm-up. Zone 2 (60-70%): Fat burning, easy endurance. Zone 3 (70-80%): Aerobic endurance. Zone 4 (80-90%): Threshold/speed training. Zone 5 (90-100%): Maximum effort, sprint intervals.

Measure your pulse first thing in the morning before getting out of bed. Count beats for 60 seconds, or 15 seconds and multiply by 4. Average several mornings for the most accurate result. Normal resting HR is 60-100 bpm.

For fat loss, spend most time in Zone 2. For endurance, mix Zone 2 and 3. For speed and performance, include Zone 4 intervals. Zone 5 should be used sparingly for short, intense efforts.

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The Science of Heart Rate Training Zones

Heart rate zones are intensity brackets based on your maximum heart rate (MHR). The 220-minus-age formula for estimating MHR is a rough population average with a standard deviation of 10-12 bpm — meaning your actual MHR could be 20+ beats different from the estimate. If you train seriously, a graded exercise test or field test provides a much more accurate baseline for zone calculations.

Why the Karvonen Formula Is Better

Simple percentage-of-max calculations ignore your fitness level. Two people with the same max HR of 190 but resting rates of 50 (fit) and 80 (sedentary) have very different working ranges. The Karvonen formula accounts for this by using heart rate reserve (HRR = Max HR - Resting HR) as the basis for zones. A person with a lower resting HR has a larger reserve and wider training zones, reflecting their higher cardiovascular fitness.

Training Zone Strategy

Elite endurance athletes spend roughly 80% of training time in Zone 1-2 and only 20% in high-intensity zones (the "polarized training" model). Recreational athletes often make the mistake of spending too much time in Zone 3 — hard enough to feel tired but not intense enough to trigger significant adaptation. The result is chronic fatigue without proportional improvement. For most goals, train easy days truly easy (Zone 2) and hard days truly hard (Zone 4-5).