How to use it
- Type your Age in years.
- Measure your Resting heart rate on waking, and enter it in beats a minute.
- Enter a Measured maximum heart rate (optional) only if you have one from a supervised test; otherwise leave it empty.
- Read the Karvonen target at each intensity table to find the row for your planned effort.
How the target is calculated
The Karvonen method, published by Karvonen and colleagues in 1957, sets exercise intensity as a share of the heart rate reserve: the gap between the maximum and the resting heart rate. The target is the reserve times the intensity, plus the resting rate (Wikipedia, Heart rate). Adding the resting rate back means that a fitter person, with a lower resting rate, gets a wider range.
The maximum comes from the Tanaka formula, 208 minus 0.7 times age. Tanaka, Monahan and Seals (2001) pooled 351 studies with 18,712 subjects and found the formula holds in healthy adults of both sexes. They also found that the older 220 minus age formula underestimates the maximum in older adults.
These targets are estimates and not medical advice. The formula gives an average for people of the same age, and a supervised maximal test is the only reliable way to measure your own maximum. If you have a heart condition, get a doctor's advice on training limits before you use any target.
Maximum (Tanaka): HRmax = 208 - 0.7 x age
Reserve: HRR = HRmax - resting heart rate
Target: target = HRR x intensity + resting heart rate
Example, age 40, resting 60, 70%: 180 - 60 = 120; 120 x 0.70 + 60 = 144 beats a minuteKarvonen and the other zones
Karvonen targets are one way to set intensity. The heart rate zone calculator also shows the percent-of-maximum method, which ignores the resting rate, and it gives the same 50 to 90 percent table. Named zones such as zone 2 differ between coaches and textbooks, so use the boundaries your coach or doctor uses.
What this calculator does not include
- Medicines such as beta-blockers, which lower the heart rate.
- Heat, caffeine, stress, illness and tiredness, which change the heart rate on a given day.
- Heart rhythm problems and heart disease, which need a medical assessment before you train. Children and people under 18 are outside the age range of the formula.
Worked example: age 40, resting 60, Karvonen
Maximum heart rate: 208 − 0.7 × 40 = 180 beats a minute.
Heart rate reserve: 180 − 60 = 120 beats a minute.
Target at 70%: 120 × 0.70 + 60 = 144 beats a minute.
| Intensity | Target (beats a minute) |
|---|---|
| 50% | 120 |
| 60% | 132 |
| 70% | 144 |
| 80% | 156 |
| 90% | 168 |
Frequently asked questions
How accurate is the Tanaka formula for me?
It is an average for healthy adults of your age. Individual maximums vary widely, so your own maximum can be higher or lower. A supervised maximal test is the only reliable way to measure it.
Why use Karvonen rather than a percentage of the maximum?
Karvonen takes your resting heart rate into account, so the target depends on your fitness as well as your age. The percent-of-maximum method, on the heart rate zone calculator, does not use the resting rate.
When should I measure my resting heart rate?
On waking, before you get up, when you are calm and rested. Heat, illness and stress can change the reading, so note the conditions if your readings vary.
What if my heart rate is different from the table?
The table is an estimate. Heat, sleep, caffeine, stress and some medicines change your heart rate, so judge the effort by your breathing and how hard it feels as well.
Does the calculator store the numbers I enter?
No. The calculation runs in your browser and nothing you enter is sent to us.
Sources
- Tanaka H, Monahan KD, Seals DR (2001): Age-predicted maximal heart rate revisited, J Am Coll Cardiol 37:153-156 (PubMed)
- Karvonen MJ, Kentala E, Mustala O (1957): The effects of training on heart rate: a longitudinal study, Ann Med Exp Biol Fenn 35:307-315 (PubMed)
- Heart rate, with heart rate reserve and the Karvonen method (Wikipedia)
Figures and text last checked on Tuesday, November 10, 2026.