Target Heart Rate Calculator
With age 40 years, resting heart rate 62 bpm, intensity 70 percent, target heart rate comes to 145 bpm — target heart rate (karvonen). It is reached in 9 steps, the last of which is 118 * 70 / 100 + 62, and each one is printed on the page with its numbers filled in. The formula is the one published by Tanaka H, Monahan KD, Seals DR, not an approximation fitted to it.
Training zones by Karvonen, which uses your resting heart rate, beside the plain percentage-of-maximum method — the two differ by nineteen beats at 70%.
Formula and sources checked · How we check
Age 40 years, Resting heart rate 62 bpm, Intensity 70, Maximum heart rate from Tanaka — 208 − 0.7 × age
145 bpm
Target heart rate (Karvonen) for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- Estimated maximum heart rate
208 - 0.7 * 40180 bpm- Heart rate reserve, max − resting
180 - 62118 bpm- Plain percentage of maximum
180 * 70 / 100126 bpm- Karvonen — reserve × intensity + resting
118 * 70 / 100 + 62144.6 bpm- Difference between the two methods
abs(144.6 - 126)18.6 bpm- Zone 2 lower bound, 60% of reserve
118 * 0.6 + 62132.8 bpm- Zone 2 upper bound, 70% of reserve
118 * 0.7 + 62144.6 bpm- Threshold work, 80% of reserve
118 * 0.8 + 62156.4 bpm- Threshold work, 90% of reserve
118 * 0.9 + 62168.2 bpm
Worked example
At 40 the Tanaka estimate of maximum is 180 bpm, and with a resting rate of 62 the reserve is 118. Seventy per cent by Karvonen is 145 bpm; the plain percentage-of-maximum method says 126 — nineteen beats lower, and low enough that a fit forty-year-old aiming there would barely be working.
How to work it out yourself
- 1.Use Karvonen if you know your resting rate. It scales the intensity across the range your heart actually has rather than across a range starting at zero, which is why the two methods diverge most for the people who are fittest.
- 2.Measure resting properly: lying down, before getting up, ideally averaged over three mornings. A figure taken sitting at a desk is 10-15 beats high and drags the whole zone up with it.
- 3.Treat the maximum as an estimate with a standard deviation of about 10 beats either way. A field test — the highest rate you actually reach in a hard effort — beats any equation, and if a zone feels wrong it probably is.
- 4.The "fat-burning zone" is real and widely misunderstood: a lower intensity burns a larger fraction of its calories from fat and fewer calories in total. For fat loss the total is what counts.
Karvonen target by intensity
| Intensity (percent) | Target heart rate (Karvonen) | Karvonen — reserve × intensity + resting | Plain percentage of maximum |
|---|---|---|---|
| 50 | 121 bpm | 121 bpm | 90 bpm |
| 60 | 133 bpm | 132.8 bpm | 108 bpm |
| 70 | 145 bpm | 144.6 bpm | 126 bpm |
| 80 | 156 bpm | 156.4 bpm | 144 bpm |
| 85 | 162 bpm | 162.3 bpm | 153 bpm |
| 90 | 168 bpm | 168.2 bpm | 162 bpm |
The formula
- Estimated maximum heart rate
208 - 0.7 * 40 - Heart rate reserve, max − resting
180 - 62 - Plain percentage of maximum
180 * 70 / 100 - Karvonen — reserve × intensity + resting
118 * 70 / 100 + 62 - Difference between the two methods
abs(144.6 - 126) - Zone 2 lower bound, 60% of reserve
118 * 0.6 + 62 - Zone 2 upper bound, 70% of reserve
118 * 0.7 + 62 - Threshold work, 80% of reserve
118 * 0.8 + 62 - Threshold work, 90% of reserve
118 * 0.9 + 62
Source: Tanaka H, Monahan KD, Seals DR — Age-predicted maximal heart rate revisited (J Am Coll Cardiol, 2001), Karvonen MJ, Kentala E, Mustala O — The effects of training on heart rate (Ann Med Exp Biol Fenn, 1957), American Heart Association — target heart rates for exercise
Questions people actually ask
- What is the Karvonen formula?
- Target = (maximum − resting) × intensity + resting. The bracket is heart rate reserve, so the intensity is applied to the range your heart can actually move through rather than to the maximum alone. It needs a resting measurement, which is why the simpler method survives.
- Is 220 minus age accurate?
- It has no published derivation and it is wrong in a predictable direction: too high for the young, too low from about 40 onwards. Tanaka’s 208 − 0.7 × age came from a meta-analysis of 351 studies and is the better default. Neither is a substitute for a measured maximum, which varies by 10-20 beats between people of the same age.
- What heart rate should I train at?
- Most endurance volume belongs at 60-70% of reserve — zone 2, the range printed above — where the effort is conversational and sustainable for hours. Threshold work sits at 80-90% and should be a small fraction of weekly time. The exact numbers matter less than not spending every session in the middle.
- Why do the two methods differ by so much?
- Because one of them knows your resting rate. Plain percentage-of-maximum implicitly assumes a resting rate of zero, so at 70% intensity it lands well below where 70% of your usable range actually is. The gap widens as resting falls, which means the fitter you are, the more misleading the simple method becomes.
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