Calculator
Enter your age to estimate your maximum heart rate and five training zones, or enter a measured maximum if you have one. The calculator starts with 208 minus 0.7 times your age, which fits large studies better than the old 220 minus age, but any age formula can be about 10 beats out for one person, and 20 or more for some. Treat the zones as a starting point and let the talk test tell you where your own zone 2 is.
Enter your age, add your resting heart rate if you know it, choose a formula or enter a measured maximum, and tick a box if you take a medicine that slows your heart or are pregnant.
180beats a minute
Fits large studies better than 220 minus age. For a typical person it can be about 10 beats a minute out either way, and 20 or more for some.
| Zone | Beats a minute | How it feels |
|---|---|---|
| Zone 1 · Very light50 to 60% of max | 90 to 108 | Relaxed, easy pace, rhythmic breathing |
| Zone 2 · Light60 to 70% of max | 108 to 126 | Comfortable pace, slightly deeper breathing, conversation possible |
| Zone 3 · Moderate70 to 80% of max | 126 to 144 | Moderate pace, harder to hold a conversation |
| Zone 4 · Hard80 to 90% of max | 144 to 162 | Fast pace and a bit uncomfortable, breathing forceful |
| Zone 5 · Maximum90 to 100% of max | 162 to 180 | Sprinting pace, can't be held for long, laboured breathing |
Watch zone 2 (60 to 70%): 108 to 126. Norway's Olympic scale (72 to 82%): 130 to 148.
Your own zone 2 is where you can still talk in full sentences. Zone 2 training
Aim for 150 minutes of moderate or 75 of vigorous activity a week. Add your resting heart rate to work these from your heart rate reserve (the Karvonen method).
It came from the legend of a figure in a 1971 review, which said the formula "defines a line not far from many of the data points". Fitting a line to those same data gives an error of 21 beats a minute.
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It was fitted to 351 studies of 18,712 people, and it doesn't underestimate older adults the way 220 minus age does. Gellish's 207 minus 0.7 × age is almost the same.
Independent tests found typical errors of about 9 to 12 beats a minute for one person, and some people are 20 to 25 beats away from their formula. A measured maximum beats any formula.
The common five zones spread through 1990s coaching scales and are watch defaults today. In research, zone 2 means just below your first threshold, which can sit anywhere from 60% to 90% of maximum heart rate. The talk test finds it without a formula.
The Karvonen method sets a target as your resting heart rate plus a percentage of the gap up to your maximum. By the American College of Sports Medicine's (ACSM's) bands, moderate is 40 to 59% of reserve (64 to 76% of maximum) and vigorous is 60 to 89% (77 to 95%).
Beta blockers, verapamil and digoxin slow the heart, so zones from a formula won't fit. In pregnancy, resting heart rate rises by about 10 to 20 beats, and guidance uses effort and the talk test instead.
Choose one, or enter a measured maximum from a maximal exercise test or the highest chest-strap reading from an all-out race or interval session, which beats any formula. At 40 the four give 180, 179, 180 and 171 beats a minute; at 60, they give 166, 165, 160 and 153 (our arithmetic).
It first appeared in 1971 in the legend of a figure, as a line drawn near about 35 data points from about 11 studies; no regression was done. Fitting a line to those same data gives 215.4 - 0.9147 × age, with an error of 21 beats a minute. Some watch makers still use it, Polar among them.
Target = resting heart rate + percentage × (maximum - resting heart rate). Percentages of reserve line up more closely with how much oxygen your body is using than percentages of maximum do, and ACSM prefers reserve when the maximum came from a maximal exercise test. With an estimated maximum, it carries the formula's error.
An example: at 40, with a maximum of 180 and a resting heart rate of 60, the reserve is 120 beats, so 40 to 59% of reserve is 108 to 131 beats a minute (our arithmetic).
Sit or lie down for five minutes first, and don't smoke or have caffeine beforehand. Count your pulse for 30 seconds and double it, or count for a full 60 seconds if it feels irregular. A normal resting heart rate is 60 to 100 beats a minute, and lower is common if you exercise a lot or take a beta blocker.
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Your maximum, with how far a formula can be out; your five zones on the watch scale or Norway's Olympic scale, with each scale's own descriptions; a zone 2 box with both versions; and a guideline box with the moderate and vigorous ranges, by heart rate reserve if you gave a resting heart rate and by percentage of maximum if not.
Beats are worked out from your unrounded maximum, and each boundary is rounded to a whole beat, so the top of one zone is the bottom of the next.
A regression through the data behind it gives 215.4 - 0.9147 × age, with an error of 21 beats a minute. In independent tests its typical error was about 10 to 12 beats (root mean square errors of 11.65 in 99 adults and 10.28 in 230), a little more than the newer formulas', and it underestimates maximum heart rate in older adults.
It fitted the averages of 492 groups from 351 studies (18,712 people), and a lab study of 514 healthy adults confirmed it (209 - 0.7 × age), with no difference by sex or activity level. In two independent comparisons, Tanaka's, Gellish's and Arena's formulas had the lowest errors. Gellish's came from 908 tests in 132 people followed for up to 25 years.
For one person, the errors were standard errors of 10.8 beats (3,320 adults in Norway's HUNT study) and 11.35 (4,796 treadmill tests), and root mean square errors of 10.7 to 11.8 and 9.2 to 10.9 for the general formulas in two independent comparisons. Every formula had limits of agreement of about 18 to 25 beats either way, and most of the single-variable formulas Robergs collected err by more than 10 beats. Fitness explained very little of the error.
In 230 adults, sex didn't change how far the formulas were out, and the Tanaka and Nes studies found no clear sex difference. Gulati's formula for women (206 - 0.88 × age), from 5,437 symptom-free women averaging 52, ran 8.2 beats low on average in 32 women averaging about 40, with the widest error of nine formulas.
Heart rate monitors reached the US market in the mid-1980s, and five named zones spread among recreational runners in the 1990s, partly through Sally Edwards' five-zone scale. Researchers call the splits within the easy and hard ranges "arbitrary". Garmin calls its five bands "the five commonly accepted heart rate zones", Polar uses the same bands, and Apple shows five zones without publishing its method.
In 16 volunteers on treadmills and bikes, the point where speech first became difficult was almost exactly the first ventilatory threshold, where breathing first deepens, and the talk test still tracked that threshold when blood donation lowered it and training raised it. A review calls it "a valid, reliable, practical and inexpensive tool" for athletes, active adults and people with heart disease, though it may not suit high-intensity intervals.
An expert panel of 14 defines zone 2 as just below the first lactate or breathing threshold. In 100 adults, the lactate threshold fell anywhere from 60% to 90% of maximum heart rate, which is why the watch zone 2 (60 to 70%) and Norway's Olympic zone 2 (about 72 to 82%) don't overlap, and why neither fits everyone.
Percentages of reserve line up with percentages of oxygen uptake reserve more closely than percentages of maximum do, and ACSM recommends reserve over percentage of maximum when the maximum came from a maximal exercise test. With an estimated maximum, one large study warns, a single formula can give a high error for any one person.
Beta blockers, verapamil and digoxin slow the heart. In heart patients taking beta blockers, a formula built for them (164 - 0.7 × age) still had a standard error of 18 beats, and in another group it underestimated their maximum by 17 beats on average. In pregnancy, average resting heart rate rises by about 10 to 20 beats and heart rate responses can be blunted, so guidance uses effort and the talk test.
The calculator shows either scale, and always shows zone 2 from both.
A common watch default: five 10% bands of maximum heart rate. These are Garmin's descriptions. Polar uses the same bands, set from 220 minus age, and Apple shows five zones as percentages of your maximum without publishing its method. The scale grew out of 1990s coaching, and the splits between zones 1 and 2 and between 4 and 5 are, in one research group's words, "arbitrary".
Olympiatoppen's intensity scale (version 2, 2024) is Norway's national five-zone scale. Each zone has a heart rate range, an effort rating and a talking cue, and athletes are asked to keep their maximum "accurate and updated", because it falls with age.
For a 40-year-old with an estimated maximum of 180 (208 - 0.7 × 40), the two scales give different zones, and their zone 2s don't even overlap:
A 2025 panel of 14 experts agreed that zone 2 training should be done "immediately below the first lactate or ventilatory threshold", the point where your breathing first deepens. In the three-zone model that much of the research uses, zone 2 is the band between the first and second thresholds, which is zone 3 on five-zone scales.
In 100 adults, the lactate threshold fell anywhere from 60% to 90% of maximum heart rate. In 16 volunteers, the breathing threshold sat at 89% of peak heart rate on the treadmill and 82% on the bike. So the same percentage can be easy for one person and hard for another.
It shows both numbers: the watch zone 2 (60 to 70% of maximum) and Norway's Olympic zone 2 (72 to 82%). At 40, with a maximum of 180, that's 108 to 126 or 130 to 148 beats a minute (our arithmetic). Your own zone 2 is where you can still talk in full sentences.
A 2025 review concluded that current evidence "does not support Zone 2 training as the optimal intensity" for building mitochondria or fat-burning capacity. Steady cardio still counts towards your weekly minutes and is easy to do a lot of; our zone 2 guide covers what it does well.
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What "moderate" and "vigorous" mean in the 150-minute guideline, from ACSM's Guidelines for Exercise Testing and Prescription (11th edition), as a 2024 review reproduces them. Effort is on Borg's 6 to 20 scale.
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Moderate activity raises your heart rate and makes you breathe faster and feel warmer: "you can still talk, but not sing". Vigorous activity makes you breathe hard and fast, and "you will not be able to say more than a few words without pausing for breath". Adults should aim for at least 150 minutes of moderate activity a week or 75 minutes of vigorous activity, and 75 vigorous minutes can give similar health benefits to 150 moderate ones.
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At 40, with an estimated maximum of 180, moderate is 115 to 137 beats a minute and vigorous 139 to 171 by percentage of maximum. Add a resting heart rate of 60 and, by heart rate reserve, moderate is 108 to 131 and vigorous 132 to 167. The calculator's guideline box does this sum for you.
After a few minutes at a steady pace, say a sentence or two out loud. The point where speech first gets harder is close to your first breathing threshold, the top of zone 2 in research terms. It needs no formula or watch, works for people with heart disease too, and is less practical in hard intervals.
Borg's 6 to 20 scale is a standard way to rate effort. Ratings of 12 to 13 (fairly light to somewhat hard) match ACSM's moderate band and 14 to 17 its vigorous band. Ratings of about 10 to 11 reflect the first breathing threshold and 13 to 15 the second, and Norway's Olympic scale gives an effort rating for each of its zones.
Heart rate lags behind the effort at the start of exercise, so it's a poor guide in short hard intervals and works best for steady efforts or intervals longer than about 4 minutes. At the same effort it can vary by about 6 to 12 beats from day to day, with altitude, heat, hydration and stress, and it drifts up in long sessions, more so in the heat. Wrist readings can be well out, so Olympiatoppen advises a chest strap.
So go by the talk test and effort when the formula may be wrong for you, when a medicine slows your heart, in pregnancy, and in short intervals.
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If you take a beta blocker or another medicine that slows your heart, such as verapamil or digoxin, heart rate zones from a formula won't fit. Use the talk test and how hard it feels instead, and ask your cardiac team if you've been given a target heart rate.
In heart patients taking beta blockers, even a formula built for them (164 - 0.7 × age) had a standard error of 18 beats a minute, and in another group it underestimated their maximum by 17 beats on average. With the medicine box ticked, the calculator puts the talk test and how hard it feels ahead of any numbers.
Methylphenidate, used for attention deficit hyperactivity disorder (ADHD), "can cause a small increase in your blood pressure and heart rate", so zones may read high: go by effort. Salbutamol inhalers can cause a "faster heartbeat that gets better quickly", so expect a higher reading soon after using one.
Average resting heart rate rises by about 10 to 20 beats from early pregnancy to delivery, and heart rate responses to exercise can be blunted, so guidance uses effort instead. Aim for "somewhat hard" (13 to 14 on the 6 to 20 scale) and a pace where you can talk but not sing. The old limit of 140 beats a minute was dropped in 1994.
The NHS says it's not recommended to start a new vigorous activity in pregnancy, such as running, and to stop if you feel uncomfortable, too hot or unwell. With the pregnancy box ticked, the calculator puts the talk test and "somewhat hard" first, and folds the zones away as less reliable in pregnancy.
Stop and call 999 (don't drive yourself to A&E) if:
Get urgent advice from NHS 111 if:
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See a GP if:
The easy cardio workout is a steady session at talk-but-not-sing pace; the build-up walk and the low-impact circuit are gentler; the intervals and the Norwegian 4x4 are the hard sessions, for when you want a harder day.
A steady 30 to 45 minute cardio session at talk-but-not-sing pace: walk, cycle, row or cross-train, counting toward weekly activity guidelines.
40 minBeginner3 movesCardio machine, A wallA 25-minute walk with short faster bouts: notice your heart and breathing speed up, then settle. A gentle way to get used to the feelings of effort.
25 minBeginner5 movesCardio machine, A wallA 25-minute standing cardio circuit with no jumping: marching, step jacks, sit-to-stands, punches, step-ups and wall push-ups, with a seated option for most moves.
25 minBeginner9 movesA bench or box, A stepA 25-minute interval session on a bike or rower: one-minute hard efforts with two minutes easy, building from 4 to 8 rounds.
25 minIntermediate1 movesCardio machineThe Norwegian 4x4, a well-studied interval session for raising VO2 max: four 4-minute hard efforts with 3 easy minutes between, on a bike, rower or treadmill.
40 minIntermediate3 movesCardio machine, A wallA common estimate is 208 minus 0.7 times your age: 180 at 40, 173 at 50 and 166 at 60. It fitted data from 351 studies better than 220 minus age. Any age formula can be about 10 beats out for you, so a measured maximum is better if you have one.
Not very. It was never derived from research: it came from a line drawn near data points in a 1971 review, and it tends to underestimate maximum heart rate in older adults. In independent tests its typical error was about 10 to 12 beats, a little more than newer formulas.
On a common watch scale, zone 2 is 60 to 70% of maximum: 108 to 126 beats a minute at 40, using 208 minus 0.7 × age. Norway's Olympic scale puts it at 72 to 82% (130 to 148). Researchers define it by your own first threshold, so check with the talk test: you should be able to speak comfortably in full sentences.
It sets targets from your heart rate reserve: resting heart rate plus a percentage of the gap between resting and maximum. It tracks effort more closely than a straight percentage of maximum, and the American College of Sports Medicine prefers it when your maximum has been measured. Add your resting heart rate to the calculator to use it; with an estimated maximum it carries the same error.
The common scale splits 50 to 100% of maximum into five 10% bands, from very light to maximum effort. It's a coaching convention from the 1990s rather than a physiological rule, and watches use it as a default. Norway's Olympic scale uses different bands, and you can switch the calculator to it.
Not by much. The largest studies found no clear difference by sex in how maximum heart rate falls with age, and sex didn't change how far formulas were out. A women's formula (206 minus 0.88 × age) is offered as an option, but it ran about 8 beats low in younger women.
Probably the talk test. Watches usually work from an estimated maximum that can be 10 or more beats out, and your first threshold can sit anywhere from 60% to 90% of maximum. If you can speak comfortably in full sentences, you're at or below your first threshold.
No: they slow your heart, so zones from a formula won't fit. In heart patients taking them, even a specially built formula was about 18 beats out. Tick the medicine box and the calculator puts the talk test and how hard it feels first; follow any target your cardiac team gives you.
There's no evidence-based limit; the old 140 beats rule was dropped in 1994. Resting heart rate rises in pregnancy, so guidance uses effort instead: aim for "somewhat hard" and keep to a pace where you can talk but not sing. Tick the pregnancy box to see the talk test first.
Between 60 and 100 beats a minute, and lower is common if you exercise a lot or take a beta blocker. Sit or lie down for five minutes, without caffeine or smoking beforehand, then count your pulse for 30 seconds and double it. See your GP if your heart is fast at rest for no obvious reason.
Estimates for healthy adults, not a personal prescription or a diagnosis, and clinical review of these pages is pending. Check with a GP before hard training or testing a maximum if you have a heart condition, high blood pressure, chest pain, dizziness or breathlessness when active, and stop for sharp or increasing pain. Health disclaimer.
