Heart Rate Zone Calculator
Find your five heart-rate training zones from age and resting heart rate. Four max-HR formulas and both the %HRmax and Karvonen methods, side by side.
About this tool
Heart-rate zones turn one number — beats per minute — into five bands you can actually train in: recovery, aerobic base, tempo, threshold and maximum. The idea is old and well established, but the number everything is computed from, your maximum heart rate, is an estimate, and the estimates disagree.
That disagreement is the point of this page. Enter your age and four published formulas are shown side by side: Fox (220 − age), Tanaka, Gulati and Nes. For a 30-year-old they land on 180, 187, 190 and 192 — a spread of 12 bpm, which is wider than half of a training zone. The tool then builds the five zones from whichever one you choose.
You also choose how the percentages are applied. Percent of max HR multiplies your maximum directly. The Karvonen method, or heart rate reserve, first subtracts your resting heart rate and then applies the percentage to the remainder — so the same 60% lands noticeably higher, because the reference range is the part you can actually use. Both are standard; mixing them up is the most common way zone numbers end up wrong. Everything runs in your browser.
Why the four formulas drift further apart as you age
All four estimators are straight lines in age but with different slopes — −1, −0.7, −0.88 and −0.64 bpm per year. They still agree for a 30-year-old within 12 bpm, but by 70 the widest pair is more than twenty bpm apart.
Fox subtracts a full beat per year, Nes only 0.64. Two people of the same age therefore get estimates that start close and separate with every birthday, and the ordering is not fixed: Fox reads above Tanaka at 30 and below it at 70, the two crossing at around 40. Gulati is the lowest line of the four and was fitted to women, which is why its gap widens with age.
The practical consequence is that a zone table built from a single formula is only as good as that formula slope for your age. Showing all four rather than quietly picking one is the honest way to present an estimate that the estimators themselves disagree about.
Why the five zones start at 50% and stop at 100%
The five bands run from 50% to 100% of the reference, so the bottom half of your heart-rate range is not called a training zone at all. Zone 1 opens at 50%; Zone 5 closes at 100%, meaning its top number is your estimated maximum heart rate itself.
The scale is defined upward from 50; below that, nothing is part of the five-zone convention, so the table simply begins at 50 rather than inventing a lower band.
The top is fixed at 100% for the same reason: the highest zone ends exactly at the maximum, so Zone 5 runs from 90% to 100% and its upper figure is the estimated maximum itself. Because every bound is a round percentage of one reference number, the whole table moves together when the formula or the basis changes.
What happens when your resting rate is at or above your maximum
The Karvonen method is refused with an error. Its whole reference is the gap between resting and maximum, and if the resting rate reaches the maximum that gap is zero or negative — there is no range left to take a percentage of.
This is a genuine edge case rather than a mistake to guard against: with a low estimated maximum and an unusually high resting rate, the two can meet. The check is resting at or above maximum, and it fires before any zone is calculated, so the page never renders a zone whose lower number is above its upper one.
Under the percent-of-maximum basis the resting rate is not read at all, so this error cannot occur there. That asymmetry is deliberate: the same input is either ignored or essential depending on which basis is chosen, and the tool makes that visible rather than quietly switching methods.
At the same 60%, the two baselines differ by 24 beats
Age 30, resting 60, maximum 187: 60% of maximum is 112 bpm, while 60% of heart-rate reserve (Karvonen) is 136 bpm, a difference of 24 beats. The gap narrows as intensity rises and must reach zero at 100%.
The two baselines use different denominators. The maximum method divides by HRmax; the reserve method divides by HRmax minus resting rate and then adds the resting rate back. The same usable range is cut into different percentages, and the divergence grows towards the low end.
The numbers: 30 beats at 50% (94 against 124), 24 at 60%, 18 at 70%, 12 at 80%, 6 at 90% and 0 at 100%. They must coincide at 100%, since both return to HRmax — which is exactly why the low intensities disagree most.
The root of it is a trade-off. Most fitness apps use the maximum method because it needs only an age; the reserve method also needs a resting rate but responds to changes in the same person, since a lower resting rate shifts the whole range up while the maximum method does not move at all.
The two are therefore not interchangeable. Compare one app zone against another and a gap of twenty-odd beats is normal, not an error on either side. This page makes the baseline an explicit choice so that difference stays visible instead of hiding in a default.
Frequently asked questions
Which maximum heart rate formula should I use?
Fox (220 − age) is what most machines and apps use, and it is the roughest — it can be off by 10 to 15 bpm for an individual. Tanaka is the better general choice, especially from mid-life on. Gulati was derived from a large sample of women and sits lower, which matters because the Fox formula tends to overestimate for women. Nes comes from a very large sample and tracks well across ages. If the four disagree a lot for you, treat the whole zone table as approximate.
What is the difference between %HRmax and Karvonen?
Reference range. Percent of max HR applies the intensity to your maximum: 60% of 190 is 114. Karvonen applies it to the reserve — the gap between resting and maximum — and then adds your resting rate back: with a resting rate of 60, 60% gives 60 + 0.6 × 130 = 138. Karvonen is generally considered the more meaningful of the two, because it accounts for fitness level, and for the same person it produces higher numbers in every zone.
Why do two zones show the same number at their edge?
Because the zones share their boundary. 60% is the top of Zone 1 and the bottom of Zone 2 — it is one number, not two. The table shows it twice on purpose so each row reads as a complete range rather than leaving you to infer the gap.
Should I use the fat-burning zone?
The fat-burning label usually sits on Zone 2, and it is true that the proportion of energy coming from fat is highest at low intensity. But total calories burned per minute rise as you go harder, so the higher zones usually burn at least as much fat overall, in less time. What Zone 2 is genuinely good for is aerobic base building and volume — the pace you can keep for a long time.
Why does my resting heart rate matter?
It sets the bottom of your reserve range. A lower resting rate generally means a larger reserve and a fitter aerobic system, and it moves every Karvonen zone up. Measure it properly — first thing after waking, before getting up, ideally averaged over several days — because a single casual reading can be 10 bpm off.
Related tools
Calculate your basal metabolic rate with three formulas side by side — Mifflin-St Jeor, Harris-Benedict and Katch-McArdle — in metric or imperial units. See why they disagree and which one fits you.
Total daily energy expenditure: BMR (Mifflin-St Jeor) times five standard activity levels, in one full table — plus calorie targets for losing, maintaining or gaining.
Solve for running pace, time or distance — enter any two and the third is worked out, with speed and both kilometers and miles shown instantly.
Work out your body mass index from metric or imperial measurements, see the WHO weight category and the healthy weight range for your height. Nothing you type leaves your browser.