A target heart rate calculator estimates the heart rate zone to aim for during exercise from your age and resting heart rate. Formula: Max HR = 220 – age. Reserve = max – resting. Zone = resting + reserve × 0.5 to resting + reserve × 0.85. A 50-year-old with a resting rate of 70 has a zone of 120 to 155 beats per minute.
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How to use the target heart rate calculator
- Enter your age.
- Enter your resting heart rate.
- Read your 50% to 85% zone and estimated maximum.
How the target heart rate calculator works
The target heart rate calculator uses the Karvonen method, which takes your resting heart rate into account. You enter your age and resting heart rate in beats per minute. It computes:
- Estimated maximum heart rate = 220 − age
- Heart rate reserve = maximum − resting
- Target = resting + reserve × intensity
It shows the zone from 50% to 85% intensity, rounded to whole beats per minute, along with the estimated maximum.
Target heart rate calculator worked example
A 50-year-old with a resting heart rate of 70 has an estimated maximum of 170 and a reserve of 100. At 50% the target is 70 + 50 = 120 bpm, and at 85% it is 70 + 85 = 155 bpm. The target heart rate calculator reports 120–155 bpm.
| Age | Resting HR | Max HR | 50% | 85% |
|---|---|---|---|---|
| 20 | 60 | 200 | 130 | 179 |
| 30 | 62 | 190 | 126 | 171 |
| 40 | 66 | 180 | 123 | 163 |
| 50 | 70 | 170 | 120 | 155 |
| 60 | 72 | 160 | 116 | 147 |
Moderate and vigorous zones
The American Heart Association and MedlinePlus describe moderate exercise as about 50% to 70% of maximum heart rate and vigorous exercise as about 70% to 85%. Those guides apply the percentages to the maximum itself, which gives lower numbers than the Karvonen method at the low end: for a 50-year-old, 50% of 170 is 85 bpm. Karvonen percentages apply to the reserve instead. Both approaches are estimates; pick one and use it consistently.
Measuring resting heart rate
Count your pulse for 60 seconds in the morning before getting up, on three or four days, and use the average. For most adults a resting rate between 60 and 100 bpm is typical, and fit people often run lower. The tool accepts a resting rate from 30 to 120 bpm and at least 20 bpm below your estimated maximum, and it shows an error otherwise.
Checking during exercise
Pause briefly and count your pulse at the wrist or neck for 15 seconds, then multiply by 4. A chest strap or watch gives continuous readings. Beginners should aim for the lower end of the zone and build up over weeks. The talk test is a simple check too: in moderate activity you can talk but not sing.
Limits of the estimate
220 minus age is only an average; real maximum heart rates vary widely between people of the same age. Medicines such as beta blockers lower heart rate, so the zone may not apply. Pregnancy, heart conditions and some illnesses also change safe ranges. If you have a health condition or are starting a new program after a long break, talk to your doctor first.
Why use heart rate reserve?
A target heart rate calculator that ignores resting rate treats everyone of the same age alike, but two people of the same age can have very different resting rates. Using the reserve, the gap between resting and maximum, scales the zone to each person. A fit 40-year-old with a resting rate of 50 gets a higher lower bound than a less fit person with a resting rate of 80, because each starts from their own baseline. This is why the method is popular with coaches and in cardiac rehabilitation.
Tracking progress
As fitness improves, resting heart rate often falls, which widens the reserve. Re-measure every month or two and update your zone in the target heart rate calculator. A rising resting rate over several days can be a sign of overtraining, poor sleep or illness, and is a reason to take an easier day.
Tips
- Measure resting heart rate on several mornings.
- Start near the low end of the zone.
- Use perceived effort alongside heart rate.
- Recalculate as your fitness changes.
For general information only, not medical advice. Your midwife, doctor or other clinician should confirm dates and care decisions.
Related converters and calculators
Related calculators:
- Calorie calculator: energy needs
- BMR calculator: metabolism
- Pace calculator: running
- One rep max calculator: strength
Sources
MedlinePlus (NIH): Give your heart a workout; American Heart Association: Target heart rates chart.
Formula and method
Max HR = 220 - age. Reserve = max - resting. Zone = resting + reserve * 0.5 to resting + reserve * 0.85.
Classic Karvonen heart-rate reserve method with 220-age max. Not medical advice.
Questions about this calculator
What formula does it use?
Karvonen: resting + (max − resting) × intensity.
How is maximum heart rate estimated?
220 minus age.
What range is shown?
50% to 85% of heart rate reserve.
What is a moderate zone?
About 50% to 70% of maximum.
Is it accurate for everyone?
No; medicines and conditions change it.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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