Target Heart Rate Calculator
Work out a training heart rate zone from the Tanaka maximum and the Karvonen reserve method, with 220 minus age shown for comparison.
Result
Enter age to see the result.
https://calcgallery.com/fitness-training/target-heart-rate-calculator/
How to use the Target Heart Rate Calculator
- Enter your age.
- Add your resting heart rate if you know it. That switches the calculation to the Karvonen reserve method.
- Set the lower and upper intensity you want the zone to span.
- Read the zone, and read what the page says about how wide the uncertainty on it is.
A safety note first
Chest pain, unusual breathlessness, dizziness or faintness during exercise are reasons to stop and see a clinician, not to check whether you are in a zone. Beta blockers and several other medications change heart rate response entirely, which makes everything below inapplicable to anyone taking them. If you have a heart condition, or you are starting exercise after a long gap or at an older age, the conversation to have is with a doctor rather than with a calculator.
How it is calculated
Two steps: estimate a maximum, then take a share of it.
The maximum. Two rules are shown.
Tanaka (2001) HRmax = 208 − 0.7 × ageFox (1971) HRmax = 220 − ageTanaka leads. His 2001 paper in the Journal of the American College of Cardiology was a meta-analysis of published data, and it found that the 220-minus-age rule underestimates maximum heart rate in older adults and overestimates it in younger ones. The Fox rule was never derived from a formal regression in the first place.
The two cross over at age forty, where both give 180. At twenty-five, Fox says 195 and Tanaka says 190.5. At sixty-five, Fox says 155 and Tanaka says 162.5 — a seven-and-a-half beat difference in the other direction.
The familiar figure is still shown, labelled for what it is, because it is the number most people arrive expecting to see.
The zone. With no resting heart rate, the zone is a straight share of the maximum. With one, the Karvonen reserve method is used instead:
reserve = HRmax − HRresttarget = HRrest + reserve × intensityKarvonen accounts for fitness in a way percentage-of-maximum cannot, because a lower resting rate produces a larger reserve and a different zone at the same nominal intensity. The page always says which method produced the answer.
Why no named training zones are shown
Most calculators label intensity bands as light, moderate and vigorous, citing ACSM’s Guidelines for Exercise Testing and Prescription. The bounds differ between editions of that book, and the specific edition being quoted could not be pinned down for this page. Rather than attribute numbers to a source that cannot be checked, the intensity bounds are entered rather than offered as named zones.
Practical tips
The uncertainty is wider than the zone. With ten to twelve beats of standard error on the maximum, a zone boundary is not a line to hold yourself to.
Perceived effort is a useful cross-check. If a zone tells you to work harder than feels sustainable for the session’s purpose, trust the feeling.
Karvonen is worth the extra measurement. It is the one adjustment here that responds to your own fitness rather than just your age.
Resting rate falls with training; maximum does not. If you track anything over time, resting heart rate is the one that will move.
A wearable’s zones may not match these. Most use their own maximum estimate and their own method, and few say which.
With your numbers
- Tanaka: 208 − 0.7 × 40 = 180 bpm, where 220 − age would give 180 bpm
- Your reserve is 180 bpm minus a resting 60 bpm
- At 50% to 70%, the zone is 120 bpm to 144 bpm
Quick reference
Any age-predicted maximum carries roughly 10 to 12 bpm of error either way. Medication, especially beta blockers, changes heart rate response entirely.
| Example | Target zone, lower |
|---|---|
| Age 25, resting 55, 60 to 75% | 136 |
| Age 30, resting 60, 50 to 70% | 124 |
| Age 40, resting 60, 50 to 70% | 120 |
| Age 40, no resting rate | 108 |
| Age 50, resting 65, 60 to 80% | 130 |
| Age 65, resting 70, 40 to 60% | 107 |
| Age 20, resting 50, 70 to 85% | 151 |
| Age 55, no resting rate | 85 |
Common questions about the Target Heart Rate Calculator
- How do I measure my resting heart rate?
- Sitting or lying quietly, ideally first thing in the morning before getting up, after several minutes of stillness. Count for a full sixty seconds rather than counting fifteen and multiplying, which quadruples any miscount. Take it on several mornings and use the average, because a single reading is affected by sleep, caffeine, alcohol and how recently you moved.
- Why do two calculators give me different zones?
- Usually because one uses 220 minus age and the other uses a better-fitting maximum, or because one uses percentage of maximum and the other uses heart rate reserve. Those two differences compound. At age forty with a resting rate of sixty, sixty percent of maximum is 108 bpm while sixty percent of reserve is 132 bpm. Neither is wrong; they are different methods, and most calculators do not say which they used.
- Is a high maximum heart rate good?
- No. Maximum heart rate is largely determined by age and genetics and has almost no relationship with fitness. It does not rise with training, and a naturally high or low maximum says nothing about your aerobic capacity. What training changes is your resting rate and how much work you can do at a given heart rate.
- What if I am on medication?
- Beta blockers reduce heart rate at rest and during exercise, often substantially, which makes every calculation on this page inapplicable. Several other medications affect heart rate response too. If you are taking anything that does, the zone here is not describing you, and the intensity you should train at is a question for the clinician who prescribed it.
- How accurate is an age-predicted maximum?
- The standard error on any age-based prediction is roughly ten to twelve beats either way, and that is a standard error rather than a worst case. At a predicted 180, a real maximum anywhere between about 160 and 200 would be unremarkable. That uncertainty is larger than the width of most training zones, which is worth keeping in view before treating a zone boundary as meaningful.