Runner Tools
Karvonen Heart Rate Calculator
Use an age estimate or your measured maximum heart rate, then add resting heart rate for a more individualized workout target.
How the Karvonen formula works
The calculation uses three steps:
- Maximum heart rate = your measured value, or 220 − age when estimating
- Heart-rate reserve = maximum heart rate − resting heart rate
- Target heart rate = reserve × intensity + resting heart rate
For a 40-year-old with a resting heart rate of 60 bpm, the estimated maximum is 180 and the reserve is 120. At 70% intensity, the result is (120 × 0.70) + 60 = 144 bpm.
How to use the result
Treat the displayed numbers as training landmarks, not rigid borders. Start near the lower end when you are new to structured training or returning from time off, then compare heart rate with breathing, perceived effort, terrain, heat, and how you feel that day.
The five reference ranges cover 50%–100% of heart-rate reserve. The range containing your selected intensity is highlighted and shows the exact target you entered. Labels are plain-language orientation only; coaches and watches divide zones differently. A boundary belongs to the range that begins there, so 70% is shown in the 70%–80% range; 100% remains in the final range.
Limitations and safety
- This adult-only calculator is not designed to estimate exercise heart rate for children or adolescents.
- The 220 − age equation is a population estimate. Your measured maximum can differ substantially.
- A measured maximum is useful only when the test truly reached maximal effort and was appropriate for you.
- Heat, dehydration, fatigue, caffeine, altitude, stress, and cardiac drift can change heart rate at a given pace.
- Beta blockers and other medications can alter the heart-rate response to exercise.
- This calculator does not diagnose health, determine exercise safety, or replace a clinician-guided target.
Stop exercising and seek appropriate care for chest pain, faintness, or unusual shortness of breath. If you have a cardiovascular condition or take heart-rate-altering medication, ask your clinician how to set exercise intensity. See our medical disclaimer.
Sources
- Karvonen and Vuorimaa (1988), Sports Medicine — heart rate and exercise-intensity application.
- American Heart Association — Target Heart Rates Chart — resting-heart-rate measurement, age-based maximum estimates, and medication cautions.
- Exercise testing in pulmonary rehabilitation — describes using a maximal exercise-test result instead of a predicted maximum in the Karvonen formula.
More runner tools
- Tinman-Style Training Pace Calculator — turn a race result into pace ranges.
- Running Pace Calculator — solve pace, time, or distance.
- VO2 Max (VDOT) Calculator — estimate current running performance.
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