How to use
- 1Enter your age, sex and resting heart rate (measured in bed after waking).
- 2Choose a max HR formula, or type a max heart rate you have measured yourself.
- 3Pick Karvonen (heart rate reserve) or simple % of max heart rate.
- 4Use the zone table to set targets for easy runs, tempo work and intervals.
Max heart rate formulas
Fox (220 − age) is the best-known rule but tends to overestimate max HR in younger and underestimate it in older adults. Tanaka et al. (2001) derived 208 − 0.7 × age from a meta-analysis of 18,712 people, and it is the default here. Gulati et al. (2010) found 206 − 0.88 × age fits women better. Every formula has a spread of roughly ±10 bpm, so a max HR measured in a hard uphill effort or race beats any formula.
Karvonen vs % of max heart rate
The Karvonen method (1957) applies the percentage to your heart rate reserve — max HR minus resting HR — and adds the resting rate back. With a max of 183 and a resting rate of 60, 70% is 60 + 0.7 × 123 = 146 bpm, versus 128 bpm with plain % of max. Karvonen accounts for fitness (a lower resting HR) and generally matches perceived effort better; % of max is simpler and is the default on many watches.
What the five zones are for
Zone 1 (50–60%) is recovery. Zone 2 (60–70%) builds the aerobic base and is where most easy running and cycling volume should sit. Zone 3 (70–80%) is steady aerobic work, Zone 4 (80–90%) is around the lactate threshold, and Zone 5 (90–100%) is for short, very hard intervals. These are general guidelines, not medical advice; heart-rate medication such as beta-blockers changes the numbers completely.
Frequently asked questions
What is zone 2 heart rate?
Zone 2 is 60–70% of your heart rate reserve (Karvonen) or of max HR. For a 35-year-old with a resting HR of 60 it is roughly 134–146 bpm by Karvonen. You should be able to talk in full sentences.
Which max heart rate formula is most accurate?
Tanaka (208 − 0.7 × age) is more accurate across ages than 220 − age; for women Gulati (206 − 0.88 × age) is a good alternative. A field-tested max is better than any formula.
How do I measure resting heart rate?
Count your pulse for 60 seconds right after waking, before getting up, on three mornings and take the average. Many fitness watches report it automatically.
Why is my heart rate above my zones on hot days?
Heat, dehydration, stress, caffeine and poor sleep all raise heart rate at the same pace (cardiac drift). On such days slow down to stay in the zone rather than chasing pace.
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