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| Zone | % of reserve | Target heart rate |
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An estimate using the 220 − age maximum, which varies by about ±10–12 bpm between individuals. Not medical advice; check with a doctor before starting intense exercise if you have a heart condition or take heart-rate-altering medication.
Find your heart-rate training zones from your age and resting heart rate, using the Karvonen method for a personalised range. Everything runs in your browser; nothing is uploaded.
How your zones are worked out
The calculator uses the Karvonen method, which bases your zones on your heart-rate reserve — the gap between your maximum and resting heart rates. First it estimates your maximum as 220 minus your age, then subtracts your resting heart rate to get your reserve. Each zone is a percentage of that reserve added back onto your resting rate: target = (max − resting) × intensity + resting. Because it includes your resting heart rate, Karvonen personalises the numbers to your fitness rather than giving everyone the same percentages of maximum.
What the five zones are for
Zone 1 (50–60%) is an easy warm-up or recovery pace. Zone 2 (60–70%), the "fat-burn" zone, is comfortable endurance work you can sustain and hold a conversation in. Zone 3 (70–80%) builds your aerobic base and is the bread-and-butter of cardio fitness. Zone 4 (80–90%) is hard, threshold-style effort that lifts performance, and Zone 5 (90–100%) is near-maximum work reserved for short intervals. A good week mixes mostly easy zones with a little time up high.
Fat-burn zone versus total calories
The fat-burn zone gets its name because a larger share of calories comes from fat at lower intensity — but higher intensity burns more calories, and more fat, overall in the same time. For losing weight, total energy balance matters most, so pair this with the calories burned calculator to see the energy cost of a session and the TDEE calculator to set your daily calories. Zones are about training the right systems, not a shortcut to fat loss. For runs, the running pace calculator converts a target pace into the session length these zones apply to, and the calorie deficit calculator turns the energy side into a weekly rate of loss.
Frequently Asked Questions
What is my target heart rate?
What is the Karvonen formula?
Which heart rate zone burns the most fat?
How do I measure my resting heart rate?
Sources
- Karvonen, M. J., et al. (1957). Heart-rate reserve method.
- Tanaka, H., Monahan, K. D., & Seals, D. R. (2001). Age-predicted maximal heart rate revisited. J Am Coll Cardiol, 37(1), 153–156 (208 − 0.7 × age); classic 220 − age (Fox).