Target Heart Rate Calculator
Training zones tell you how hard to push, and the Karvonen method is the classic way to derive them because it accounts for your individual resting heart rate rather than assuming everyone recovers alike. This calculator estimates your maximum, measures your heart rate reserve and converts any intensity band into the beats per minute you should hold during a session.
Enter values
Results
- Cardio zone (60–70% of reserve)
- 137–149 bpm
- Fat-burn zone (50–60%)
- 125–137 bpm
- Peak zone (70–80%)
- 149–161 bpm
- Maximum heart rate
- 185 bpm
- Heart rate reserve
- 120 bpm
How is the Target Heart Rate calculated?
Maximum heart rate is estimated as two hundred and twenty minus your age. Your resting heart rate is subtracted from that maximum to give heart rate reserve, the span your heart can genuinely work across during exercise. A chosen intensity percentage is applied to the reserve and your resting rate added back, which is what makes Karvonen zones more personal than simple percentages of maximum. The result is a lower and upper bound to watch during a session.
Formula
Maximum heart rate = 220 − age. Heart rate reserve = maximum − resting heart rate. Target = reserve × intensity % + resting heart rate. Zones here use 50–60% light, 60–70% moderate and 70–80% vigorous of the reserve.
Example
A 35-year-old with a resting heart rate of 65 bpm has a maximum near 185 and a reserve of 185 − 65 = 120 bpm. At moderate intensity, 60% of reserve is 72, giving 65 + 72 = 137 bpm, and 70% gives 65 + 84 = 149, so the moderate zone runs 137 to 149. The light band spans 125 to 137 and the vigorous band 149 to 161, each one only a percentage of that same 120-beat reserve.
Things to remember
Heart rate zones are scaffolding for effort, not a verdict on a workout: hills, heat and fatigue all move the numbers within a session. Take your resting heart rate on waking for a few days to get a stable input, then use the zones as rough guides while letting conversation and breathing have a vote.
Frequently Asked Questions
What is the Karvonen heart rate method?
It is a formula for training zones that works from heart rate reserve rather than maximum heart rate alone. You subtract your resting pulse from your estimated maximum, apply the desired intensity percentage to that range, then add the resting pulse back.
How do I measure my resting heart rate?
Measure it before getting out of bed by counting beats at the wrist or neck for thirty seconds and doubling. Take it over several mornings and average, since a single reading jumps with poor sleep, alcohol and stress. A consistent morning figure gives this calculator its most useful input.
Is 220 minus age accurate for maximum heart rate?
It is a rough population average with a standard deviation of around ten beats per minute, so treat it as a reference rather than a ceiling. If you want precision, a supervised max test or a field test gives a personal figure you can drop straight into the same formula.
How long should I stay in my target zone?
It depends on the session: easy work can sit in the light zone for an hour or more, while intervals spend short blocks near the top of the vigorous band with full recovery. For general health, most guidelines suggest a couple of hours a week at moderate intensity, split however suits your schedule.
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