How to use this calculator
- Enter or choose age.
- Enter or choose maximum heart rate from.
- Enter or choose method.
- Enter or choose lower intensity.
- Enter or choose upper intensity.
- The target heart rate updates as you type. Use Copy result or Share to keep it.
Method
Karvonen: THR = HRrest + (HRmax − HRrest) × intensity; % of max: THR = HRmax × intensity; HRmax (Tanaka) = 208 − 0.7 × age
- HRmax
- maximum heart rate, estimated from age or measured
- HRrest
- resting heart rate
- HRmax − HRrest
- heart-rate reserve
- intensity
- the training intensity as a fraction
Worked example
- HRmax = 208 − 0.7 × 40 = 180 bpm.
- Reserve = 180 − 60 = 120 bpm.
- Lower: 60 + 120 × 0.50 = 120 bpm; upper: 60 + 120 × 0.85 = 162 bpm.
A 40-year-old with a resting pulse of 60 would train between about 120 and 162 beats per minute at 50–85% intensity.
What the result means
The lower half of the range suits easy, longer sessions; the upper half suits harder intervals. If a measured maximum from a supervised test is available, use it: age formulas can be off by 10 bpm or more for an individual.
Assumptions and limits
- You are a healthy adult without heart conditions or heart-rate-limiting medicines such as beta-blockers.
- Maximum heart rate follows the chosen age formula unless you enter a measured value.
- Tanaka et al. (2001) found a standard deviation of roughly 10 bpm around the age prediction.
- 220 − age overestimates maximum heart rate in young adults and underestimates it in older adults.
- Heat, dehydration, caffeine and fatigue all change heart rate at a given effort.
Questions
Karvonen or percentage of max?
Karvonen accounts for resting heart rate, so two people of the same age but different fitness get different targets. Percentage of max is simpler and needs no resting measurement; at the same percentage it gives lower numbers.
Is there a special “fat-burning zone”?
At lower intensities a larger share of the energy comes from fat, but total energy used per minute is lower. For body-fat change, total weekly activity and diet matter more than the zone.
Should I check with a doctor first?
Yes, if you have heart, lung or metabolic disease, symptoms on exertion, or take medication that affects heart rate.
Sources
Please note: This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.