Karvonen Heart Rate Calculator
Calculate an exercise heart rate range using the Karvonen heart rate reserve method. You can estimate your maximum heart rate from age or enter a maximum heart rate you already know.
See how this was calculated
Heart rate reserve reference ranges
For comparison, federal physical activity guidance describes moderate and vigorous relative intensity using the following heart rate reserve ranges.
| Relative intensity | % of HRR | Your calculated range |
|---|---|---|
| Moderate | 40% to 59% | |
| Vigorous | 60% to 84% |
These are relative intensity categories, not individualized exercise prescriptions or safety limits.
How the Karvonen heart rate calculator works
The Karvonen method calculates exercise heart rate from your heart rate reserve. Heart rate reserve is the difference between maximum heart rate and resting heart rate.
This means two people with the same maximum heart rate can receive different calculated exercise ranges if their resting heart rates are different.
Karvonen formula
Heart rate reserve:
HRR = Maximum heart rate − Resting heart rate
Target heart rate:
Target HR = Resting HR + (Intensity × HRR)
In plain English, subtract resting heart rate from maximum heart rate, multiply the difference by the chosen intensity, then add resting heart rate back.
How maximum heart rate is estimated
If you choose the age based option, this calculator estimates maximum heart rate with the equation:
Estimated maximum HR = 208 − (0.7 × age)
This equation comes from research by Tanaka, Monahan and Seals that analyzed data from healthy adults. It is still an estimate. Individual maximum heart rate can differ from an age based prediction.
If you already have a measured maximum heart rate from an appropriate exercise assessment, the calculator lets you enter that value instead of estimating it from age.
Worked example
Suppose a 40 year old has a resting heart rate of 60 bpm and wants to calculate a range from 60% to 80% of heart rate reserve.
Estimated maximum heart rate: 208 − (0.7 × 40) = 180 bpm
Heart rate reserve: 180 − 60 = 120 bpm
At 60% HRR: 60 + (0.60 × 120) = 132 bpm
At 80% HRR: 60 + (0.80 × 120) = 156 bpm
The calculated range is therefore 132 to 156 bpm.
Heart rate reserve versus percentage of maximum heart rate
These two methods are not interchangeable. A percentage of heart rate reserve is applied after subtracting resting heart rate. A percentage of maximum heart rate is applied directly to maximum heart rate.
For example, the U.S. Physical Activity Guidelines describe relative moderate intensity as 40% to 59% of reserve and vigorous intensity as 60% to 84% of reserve. By comparison, widely used maximum heart rate guidance often expresses moderate and vigorous intensity using percentages of maximum heart rate instead.
Therefore, entering a percentage intended for one method into a calculator using the other method can produce a different result.
How to get a useful resting heart rate value
Resting heart rate should represent your pulse while you are genuinely at rest rather than immediately after walking, exercise, caffeine, stress or another activity that raises your pulse.
The American Heart Association notes that a useful time to check resting heart rate is in the morning after sleep and before getting out of bed. Your usual resting rate can also vary with fitness, stress, medication and other factors.
Common mistakes
- Using a heart rate measured after activity as the resting heart rate.
- Treating an age predicted maximum heart rate as an exact personal maximum.
- Confusing percentage of heart rate reserve with percentage of maximum heart rate.
- Entering a resting heart rate that is equal to or higher than the maximum heart rate.
- Treating the calculated range as a medical safety limit.
Why might another calculator give a different result?
Maximum heart rate can be estimated with different equations. This calculator uses the Tanaka equation when age based estimation is selected. Some other calculators use the older 220 minus age formula.
Results can also differ because calculators use different intensity percentages, round at different stages, or calculate percentages of maximum heart rate instead of heart rate reserve.
Important limitations
Heart rate formulas provide estimates. They cannot determine whether a particular exercise intensity is medically appropriate or safe for an individual.
Heart rate response can also be affected by medication and health conditions. The American Heart Association specifically notes that some medications can alter heart rate and therefore change a person's appropriate exercise heart rate.
If a healthcare professional has given you a specific exercise heart rate range, use that individualized guidance rather than replacing it with a general calculator.
Methodology
The calculator first determines maximum heart rate. If age based estimation is selected, it uses the Tanaka equation of 208 minus 0.7 times age. If a known maximum is entered, that value is used directly.
It then subtracts resting heart rate from maximum heart rate to obtain heart rate reserve. Each selected intensity percentage is multiplied by the reserve, and resting heart rate is added back to produce the calculated exercise heart rate.
Displayed heart rates are rounded to the nearest whole beat per minute. Calculations are performed locally in the browser and entered values are not stored or transmitted by this implementation.
Sources
- Karvonen, Kentala and Mustala, 1957, research on exercise training and heart rate.
- Tanaka, Monahan and Seals, age predicted maximum heart rate research published in the Journal of the American College of Cardiology.
- Physical Activity Guidelines for Americans, relative exercise intensity classifications.
- American Heart Association target heart rate guidance, including resting heart rate measurement and factors that can affect exercise heart rate.
Methodology last reviewed: September 23, 2026