Target Heart Rate (Karvonen)
Instead of taking a percentage of maximum heart rate, the Karvonen method takes a percentage of heart rate reserve — max minus resting. It suits fitter people with low resting rates better.
Your numbers
Zone low
148bpm
Zone high
160bpm
Max heart rate
184bpm
What it means
70% intensity is the aerobic development zone.
Formula
Zone low = (Max heart rate − Resting HR) × Intensity ÷ 100 + Resting HR (Karvonen)
Measure resting heart rate lying down, immediately after waking, for an accurate figure.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| AgeAge in completed years — it shifts by one depending on the birthday. | 35 | 5 ~ 100 |
| Resting HR (bpm)Resting heart rate, taken right after waking. | 65 | 30 ~ 120 |
| Intensity (%)What share of your maximum heart rate you are working at. | 70 | 40 ~ 95 |
Step by step
Quick reference table
Results when only Age changes and everything else stays put.
| Age | Zone low (bpm) | Zone high (bpm) | Max heart rate (bpm) |
|---|---|---|---|
| 17.5 | 157 | 170 | 196 |
| 26.3 | 152 | 165 | 190 |
| 35 | 148 | 160 | 184 |
| 52.5 | 139 | 150 | 171 |
| 70 | 131 | 140 | 159 |
What each result means
| Result | At default values |
|---|---|
| Zone low (bpm)The bottom of the heart-rate band. | 148 |
| Zone high (bpm)The top of the heart-rate band. | 160 |
| Max heart rate (bpm)Maximum heart rate estimated from age; individual variation is large. | 184 |
Common mistakes
Measure resting heart rate lying down, immediately after waking, for an accurate figure.
Glossary
- Age
- Age in completed years — it shifts by one depending on the birthday.
- Resting HR
- Resting heart rate, taken right after waking.
- Intensity
- What share of your maximum heart rate you are working at.
- Zone low
- The bottom of the heart-rate band.
- Zone high
- The top of the heart-rate band.
- Max heart rate
- Maximum heart rate estimated from age; individual variation is large.
Frequently asked questions
Q. How is Target Heart Rate (Karvonen) calculated?
Zone low = (Max heart rate − Resting HR) × Intensity ÷ 100 + Resting HR (Karvonen) — Instead of taking a percentage of maximum heart rate, the Karvonen method takes a percentage of heart rate reserve — max minus resting. It suits fitter people with low resting rates better.
Q. Can you walk through an example?
With Age 35, Resting HR 65bpm, Intensity 70%, the answer is Zone low 148bpm.
Q. What do I need to enter?
Enter Age, Resting HR, Intensity. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Age moves the answer to Age 17.5 → Zone low (bpm) 157 and Age 70 → Zone low (bpm) 131. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Measure resting heart rate lying down, immediately after waking, for an accurate figure.
Related calculators
These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.