What is the Karvonen method?

The Karvonen method calculates target heart rate as: (Max HR − Resting HR) × intensity% + Resting HR. By accounting for resting heart rate (heart rate reserve), it produces personalised zones that reflect individual cardiovascular fitness.

What is heart rate reserve?

Heart rate reserve (HRR) is the difference between your maximum heart rate and your resting heart rate. A higher HRR indicates better cardiovascular fitness. The Karvonen method uses HRR as the basis for intensity calculations.

When should I measure my resting heart rate?

Measure resting heart rate first thing in the morning before getting out of bed, after at least 5 minutes of rest. Take the average over 3–5 days for the most reliable reading.

Does the calculator keep what I enter?

The values exist only in the open page and are not written to browser storage, so reloading the page clears them. All calculations run in your browser. Our servers are not involved at any point.

Target heart rate calculator

Enter your age and resting heart rate to calculate personalised target heart rate zones using the Karvonen method. This accounts for your individual fitness level, producing more accurate zones than simple percentage-of-max formulas.

Age (years)

Resting heart rate (bpm) optional

Results are for informational purposes and do not constitute medical advice.

How it works

With a resting heart rate entered, each zone boundary becomes resting HR + intensity × (max HR − resting HR), the Karvonen method. For a 40-year-old with a resting rate of 60 bpm, max HR is 180 and the reserve is 120 bpm, so the 60 to 70 percent zone becomes 132 to 144 bpm instead of 108 to 126 bpm on the plain percentage-of-max scale. The resting rate must be between 20 and 220 bpm and below your estimated max. All arithmetic runs locally in your browser.

Processing runs in your browser

All calculations happen locally using pure JavaScript. Our servers are not involved at any point.

Technical specification

The Tanaka formula (208 − 0.7 × age) was derived from a meta-analysis of 351 studies involving 18,712 subjects by Tanaka et al. and published in the Journal of the American College of Cardiology 37:1 (2001). It corrects the classic 220 − age formula, which overestimates maximum heart rate in younger adults and underestimates it in older adults; the two agree at age 40. Both formulas have a standard deviation of ±10–12 bpm. The Karvonen method uses heart rate reserve (HRR = Max HR − Resting HR) to scale zones relative to individual fitness.

Max HR formula: Tanaka: 208 − 0.7 × age (JACC 37:1, 2001)
Personalised zones: Karvonen method using heart rate reserve
Accuracy: ±10–12 bpm (population average)
Browser API: Pure JavaScript arithmetic. No library

Related operations

For estimating daily energy expenditure for training, try the calorie calculator. To capture a baseline weight category, use the BMI calculator. For tracking strength gains alongside cardio zones, see the one-rep max calculator.

Frequently asked questions

What is the Karvonen method?: The Karvonen method calculates target heart rate as: (Max HR − Resting HR) × intensity% + Resting HR. By accounting for resting heart rate (heart rate reserve), it produces personalised zones that reflect individual cardiovascular fitness.
What is heart rate reserve?: Heart rate reserve (HRR) is the difference between your maximum heart rate and your resting heart rate. A higher HRR indicates better cardiovascular fitness. The Karvonen method uses HRR as the basis for intensity calculations.
When should I measure my resting heart rate?: Measure resting heart rate first thing in the morning before getting out of bed, after at least 5 minutes of rest. Take the average over 3–5 days for the most reliable reading.
Does the calculator keep what I enter?: The values exist only in the open page and are not written to browser storage, so reloading the page clears them. All calculations run in your browser. Our servers are not involved at any point.

Last reviewed September 30, 2026

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