What are heart rate training zones?
Heart rate training zones are ranges of beats per minute tied to percentages of an individual's maximum heart rate, each associated with a different kind of effort. The five-zone model used almost everywhere divides the range from 50% to 100% of maximum into five bands: recovery, base, tempo, threshold and maximum. The point of the model is not that physiology divides neatly into five boxes — it does not — but that a single number is easier to train against than a feeling.
The maximum heart rate is the anchor, and it is where most of this goes wrong. The famous 220 minus age formula comes from a 1971 paper that fitted a line by eye to a handful of small studies; measured against real laboratory maximums it carries a standard deviation of about ten to twelve beats. That is enough to place a whole zone wrongly. Better formulas exist — Tanaka's 208 minus 0.7 times age came from a meta-analysis, Nes's from a cohort of nearly 3,000, and Gulati's specifically from a study of more than 5,000 women — and they disagree with each other by several beats at the same age, which is worth seeing rather than being told.
The second input, resting heart rate, matters more than most people expect. The Karvonen method, which this calculator uses when you supply one, computes zones from the heart rate reserve — the gap between resting and maximum — rather than from maximum alone. A trained cyclist with a resting rate of 45 beats per minute has a much larger reserve than an untrained person of the same age, so identical percentages produce noticeably different target numbers. Percentages of maximum alone systematically overstate the easy zones for fit people.
How to find your training zones
- Enter your age. That alone produces a set of zones, calculated as percentages of an estimated maximum.
- Add a resting heart rate, measured on waking before getting up and averaged over three mornings, to switch the calculation to the Karvonen method.
- If you know your real maximum — from a supervised test or a hard race — enter it. Measured data beats every formula here.
- Choose which published formula to estimate from if you have no measured figure, and look at the comparison table under the results to see the spread.
- Read the zone table and note the two you will actually live in: most endurance training belongs in the base zone, with a minority at threshold and above.
- Check the zones against the talk test on your next session — if you cannot speak in full sentences in the base zone, the numbers are set too high.
Heart Rate Zones limits and rules
| Item | Limit |
|---|---|
| Zones | Five, from 50–60% to 90–100% of maximum |
| Method | Percentages of maximum, or Karvonen when a resting heart rate is supplied |
| Maximum heart rate formulas | Tanaka, Fox, Gulati (women) and Nes — all age-only estimates |
| Typical error | Around ±10–12 bpm for the age formulas, which is most of a zone's width |
| Resting heart rate | Accepted between 25 and 120 bpm; measured on waking, averaged over several mornings |
| Measured maximum | Accepted between 60 and 230 bpm when you have a real figure |
| Age limit | Under 120 years; the formulas are linear and were never fitted below about 10 |
| Not modelled | Medication, altitude, heat, caffeine, illness, fitness changes or cardiac conditions |
When to use it
- Setting a base-zone ceiling for long easy runs so that easy days are genuinely easy.
- Programming intervals by heart rate rather than by feel on a treadmill where pace is unreliable.
- Checking how much easy work you are actually doing — most people find it is far less than they think.
- Getting a first training range before spending money on a lab test.
- Working out whether a resting heart rate that has drifted upwards over a fortnight signals fatigue or illness.
Is it private?
Your age, resting pulse and any measured maximum stay in the page. The calculation is a handful of arithmetic operations in JavaScript and nothing is transmitted, stored or logged — there is no request to watch in the network panel because there is none to make.
Frequently asked questions
Tanaka's 208 minus 0.7 times age is the best default for most adults, because it came from a meta-analysis of 351 studies rather than from a small convenience sample. If you are a woman, Gulati's 206 minus 0.88 times age was derived from more than 5,000 women and usually lands a few beats above the others. The honest answer, though, is that all of them are estimates with a spread of around ten beats either way, and a measured maximum — from a supervised test or a hard race — is worth more than the choice between formulas.
Because the calculation switches method. Without a resting rate, zones are straight percentages of maximum, so a very fit person and an unfit person of the same age get identical numbers. The Karvonen method instead uses the heart rate reserve — maximum minus resting — and adds the resting rate back afterwards. For somebody whose resting pulse is 45 rather than 70, that produces noticeably lower numbers in the easy zones, which is the correct answer: their heart does more work per beat, so a given percentage of maximum is a smaller fraction of their actual capacity.
The percentages are conventions; the underlying physiology is a continuum. Lactate threshold sits at a different percentage of maximum in every individual, and it moves with training, fatigue, heat and caffeine. What the zones give you is a consistent vocabulary and a ceiling to test against. Use the talk test as an independent check: if you cannot hold a full conversation at the top of the base zone, your true maximum is probably lower than the estimate, or fatigue is distorting your heart rate response.
No, and the enthusiasm for it has been overcorrected. The evidence is good that a large volume of easy work builds aerobic fitness efficiently and is far more sustainable than constant hard effort, which is why base training dominates most serious training plans. But threshold and high-intensity work produce adaptations that easy running does not, and the classic pattern is a large majority of easy volume with a small, deliberate slice of hard work each week. Doing only easy sessions leaves real fitness on the table; doing only hard ones leaves you injured.
Some do, substantially. Beta blockers slow the heart directly, so every zone in the table will be too high and exercising to those numbers is not advised without medical guidance. Some antidepressants, cold remedies, thyroid medicines and stimulants push heart rate the other way. Illness, dehydration, alcohol and altitude all shift it temporarily as well. If you take anything with a cardiac effect, the zones need a clinician's input rather than a formula.
A resting rate in the 40s and 50s is normal in well-trained endurance athletes and is not a concern on its own. A rate consistently above 100 at rest, or a sudden unexplained change in either direction — especially with dizziness, breathlessness or palpitations — is a reason to see a doctor. This calculator will happily compute zones around whatever you type and cannot tell the difference between a trained heart and a sick one.
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Written and maintained by Md. Nur Hossain Repon.