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Heart Rate Zone Calculator
Work out your five training heart rate zones from your age, with your resting rate for the Karvonen method and a choice of max HR formula. Runs in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Estimated maximum heart rate
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Measure it on waking, before getting up.
From a lab test or a supervised maximal effort.
Example shown — enter your own details.
| Zone | Beats per minute | What it is for |
|---|
These are population estimates for healthy adults, not medical advice. Individual maximum heart rates vary widely from any formula, and some medications — beta blockers in particular — lower your heart rate substantially, which makes age-based zones meaningless. If you have a heart condition, are on such medication, or are new to hard exercise, get your zones from a doctor or an exercise physiologist.
How it works
- Enter your age, and your resting heart rate if you know it.
- Pick a formula for your maximum, or enter a measured one if you have it.
- Choose whether zones are percentages of your maximum or of your heart rate reserve.
- Read the five zones, each with the beats per minute and what that intensity is for.
Two ways to slice the same range
Both methods produce five zones, but they measure from different starting points:
percent of max: target = max × intensity
Karvonen: target = resting + (max − resting) × intensity
For a 40-year-old with a resting rate of 60 and an estimated maximum of 180, the reserve is 120 bpm. Zone 2 — 60–70% — comes out as 108–126 bpm by percentage of max, but 132–144 bpm by Karvonen. That is not a rounding difference; it is a genuinely different target, because Karvonen only counts the range you can actually move through. Mixing the two between sessions is why some training logs never make sense.
Why the formulas disagree, and where
The classic estimate and the Tanaka equation cross at exactly age 40, and diverge steadily either side of it:
age 20 → 220−age gives 200, Tanaka 194 (6 lower)
age 40 → both give 180 (identical)
age 70 → 220−age gives 150, Tanaka 159 (9 higher)
Solving 220 − age = 208 − 0.7 × age gives age = 40 exactly, which is a neat coincidence of the two fits rather than anything physiological. The practical consequence is real though: the classic formula overestimates for younger people and underestimates for older ones, so a 65-year-old following it would train zone 2 at 93–109 bpm when Tanaka suggests 98–114.
This is also why the zones are worth sanity-checking against effort. If your "easy" zone leaves you gasping, or your threshold zone feels like a stroll, your real maximum differs from the estimate — and your body is the better instrument.
FAQ
How accurate is 220 minus your age?
As a population average it is reasonable; as a prediction for you it is not. Individual maximum heart rates scatter widely around any age-based formula — two healthy 40-year-olds can genuinely differ by 20 beats or more. Treat every figure here as a starting point to be corrected by how the effort actually feels.
Which formula should I choose?
Tanaka (208 − 0.7 × age) fits the population data better than the classic one, particularly away from middle age. Gulati was derived specifically from data on women, where the classic formula tends to overestimate. If you have a measured maximum from a proper test, use that — it beats every estimate.
What is the Karvonen method and why do its zones look higher?
It takes percentages of your heart rate reserve — the gap between resting and maximum — then adds your resting rate back on. Because it starts from your resting rate rather than from zero, the zones sit higher and are narrower. For a 40-year-old with a resting rate of 60, zone 2 starts at 132 bpm by Karvonen versus 108 by percentage of max.
Which basis should I train by?
Percentage of max is what most watches display, so it is the easier one to follow in practice. Karvonen adapts to your own resting rate, which makes it more personal — and as your resting rate falls with fitness, your zones shift with it. Pick one and stay with it; mixing the two makes your training log meaningless.
Why is zone 2 talked about so much?
Because it is the pace you can hold for a long time while still being able to talk, and most endurance plans put the bulk of their hours there. The practical test is conversational effort — if you cannot speak in full sentences, you have drifted into zone 3, which is the most common training mistake.
I take beta blockers. Do these zones apply?
No. Beta blockers lower both your resting and your maximum heart rate substantially, so any age-based estimate will be far too high and training to it would be genuinely unsafe. The same applies to some other cardiac medications. Your zones need to come from a clinician who knows your prescription.
How we compare
| Feature | Online Tool Store | Fitness site calculators | Lab test with a physiologist |
|---|---|---|---|
| Offers more than one max HR formula | ✓ | Usually just 220 − age | Measures it directly |
| Both percent-of-max and Karvonen | ✓ | Rarely both | ✓ |
| Says how uncertain the estimate is | ✓ | ✗ | ✓ |
| Nothing about you leaves your device | ✓ | Often behind a signup | Confidential, but recorded |
| Accounts for medication and heart conditions | Explicitly out of scope | Rarely mentioned | ✓ |
| Gives your true maximum and lactate threshold | ✗ | ✗ | ✓ |
A sensible starting point for structuring easy and hard days, with the choice of formula and basis made explicit instead of hidden. It cannot measure your actual maximum, and it is the wrong tool entirely if you take heart-rate medication — for either of those, a proper test or a clinician is the answer.