Heart rate zone calculator

By Rick Campbell · Updated 12 Sept 2026 · Sourced to primary literature · Not medical advice

Heart rate zones split the range between sitting still and going flat out into five bands, each of which asks something different of your body. This page estimates your maximum heart rate from your age, divides it into those five zones, and, if you tell it your resting pulse, shows the same zones calculated the other common way, from your heart-rate reserve.

It also does something most zone calculators skip: it tells you how wrong the answer might be. Every age-based prediction of maximum heart rate carries a standard deviation of roughly eleven beats per minute. That is not a rounding error. It is enough that two people of the same age, both perfectly healthy, can have true maximums twenty-five beats apart, and a zone table built on the average will put one of them a whole zone out.

So use the numbers here as a starting frame, not a prescription. They are genuinely useful for structuring a week of training and for spotting when you are riding too hard on easy days, which is the most common mistake in endurance training. They are not a substitute for a measured maximum, and they stop being meaningful altogether on rate-controlling medication.

In brief

Maximum heart rate is estimated from age: Tanaka gives 208 − 0.7 × age, Gellish 207 − 0.7 × age, and the familiar 220 − age is the least accurate of the three.
Any age-predicted maximum has a standard deviation of about 11 bpm, so roughly one adult in three sits outside the predicted value ±11.
Percentage-of-maximum zones and Karvonen (heart-rate reserve) zones are both standard, and Karvonen always gives higher target beats for the same zone.
Most endurance plans put 70–80% of training time in zones 1–2 and keep zones 4–5 to one or two sessions a week.
Beta blockers, pacemakers, atrial fibrillation and many heart conditions make age-predicted zones invalid; intensity has to be set by perceived exertion or a supervised test instead.

What you'll see here

Your estimated maximum heart rate with its ±11 bpm band, the five training zones in beats per minute, all three age-prediction equations compared, and, if you add a resting pulse, your heart-rate reserve and the Karvonen version of every zone.

The five heart rate training zones and what each is for
Zone	% of maximum heart rate	What it trains	How it feels
Zone 1: very light	50–60%	Warm-up, cool-down and recovery between hard days	You could hold a full conversation, or sing badly
Zone 2: light	60–70%	The aerobic base most endurance plans spend the majority of their hours in	Comfortable, nose-breathing, sentences without effort
Zone 3: moderate	70–80%	Aerobic capacity and tempo work; efficient but tiring	Short sentences only: the classic 'comfortably hard'
Zone 4: hard	80–90%	Threshold and interval work that raises the ceiling on sustainable pace	A few words at a time; you are watching the clock
Zone 5: maximum	90–100%	Short, sparing bursts for peak power and VO₂max	No talking. Minutes, not tens of minutes

The percentage bands follow the ACSM percentage-of-maximum scheme used throughout exercise prescription. Enter your age above to turn them into beats per minute, and add a resting heart rate to see the Karvonen (heart-rate reserve) version alongside.

What heart rate zones are and what they are for

Heart rate is a proxy for how hard your cardiovascular system is working. Below a certain intensity you are burning mostly fat, breathing easily and could keep going for hours; above another, you are running on stored glycogen, accumulating lactate faster than you clear it, and counting down the minutes. Zones are an attempt to mark those transitions on a dial you can actually read while exercising, by expressing intensity as a percentage of your own maximum rather than in absolute beats.

The practical value is not precision. It is discipline. Left to feel alone, most people drift into the middle: easy sessions creep up to moderately hard, hard sessions settle for moderately hard, and the week becomes one flat block of effort that is too taxing to recover from and not stimulating enough to drive adaptation. A zone table gives easy days a ceiling and hard days a floor. That single structural change is worth more than any refinement of where the boundaries sit.

The five-zone scheme used here follows the percentage-of-maximum convention in ACSM's exercise prescription guidelines: 50–60%, 60–70%, 70–80%, 80–90% and 90–100% of maximum heart rate. Other systems exist (three-zone models built around ventilatory thresholds, seven-zone cycling models built around functional threshold power) and they are not interchangeable. If your coach or watch uses a different scheme, use theirs rather than mixing the two.

How to measure your resting heart rate properly

Resting heart rate sounds simple and is routinely measured wrong. It means your heart rate at genuine rest: awake, lying or sitting quietly, before you have stood up, eaten, drunk coffee or checked your phone. Measured that way it is one of the more useful numbers you can track at home: it falls as aerobic fitness improves, and a sustained rise of five or more beats is an early flag for illness, dehydration, poor sleep or accumulated training fatigue.

Take it first thing in the morning, before getting out of bed. Find the pulse at your wrist below the base of the thumb, or at the side of the neck, and count for a full sixty seconds rather than counting fifteen and multiplying: short counts multiply their own error by four. Do this on three or four consecutive mornings and average the readings, because a single morning can be skewed by a bad night, a late meal or a glass of wine.

A wrist tracker's overnight or waking figure is usually close enough, and often better than a hand count because it averages many hours. Be aware that most devices report the lowest sleeping value, which typically runs a few beats below a waking seated count; whichever you use, use the same one every time. Typical adult resting rates sit between 60 and 80 beats per minute, with trained endurance athletes commonly in the 40s and 50s, but the useful comparison is with your own previous readings, not with anyone else's.

Count for a full minute, not fifteen seconds: a two-beat miscount becomes an eight-beat error.
Average three or four mornings; single readings swing by five beats on sleep and hydration alone.
Caffeine, alcohol, illness, a hot room and stress all push it up; none of them mean your fitness changed.
A resting rate persistently above 100 at genuine rest, or an unexplained drop with dizziness, is worth a GP appointment rather than a calculator.

Percentage of maximum versus heart-rate reserve

There are two standard ways to turn a maximum heart rate into a target, and they give different answers. The simple one takes a straight percentage of maximum: 70% of a 180 bpm maximum is 126 bpm. The Karvonen method, published in 1957, takes the percentage of your heart-rate reserve (the range between resting and maximum) and adds your resting rate back on: with a resting pulse of 58, that same 70% becomes ((180 − 58) × 0.70) + 58 = 143 bpm.

The seventeen-beat gap is not an error in either method. They are answering slightly different questions. Percentage of maximum scales the whole dial, including the portion of it your heart never uses because it never goes below resting. Karvonen scales only the working range, which is why it is the method used in cardiac rehabilitation and by most coaches: it adapts automatically to the person, so a fit athlete with a resting rate of 45 and an unfit beginner with a resting rate of 80 get appropriately different targets from the same predicted maximum.

This calculator shows both when you enter a resting pulse, so you can see the size of the difference on your own numbers. What matters is picking one and staying with it. Comparing a Karvonen target from your coach against a percentage-of-maximum zone on your watch is how people end up convinced they are training in zone 2 while actually spending the session in zone 3.

How accurate an age-predicted maximum really is

Not very, for an individual. Tanaka, Monahan and Seals pooled 351 studies covering 18,712 people and added a laboratory validation of 514 more, and arrived at HRmax = 208 − 0.7 × age. Their regression fitted the group average well and did not differ between men and women, but the scatter around it was wide: the standard deviation of individual maximums around the predicted line runs to roughly ten or eleven beats per minute. Gellish and colleagues, following 132 adults across 25 years and 908 exercise tests, produced the near-identical 207 − 0.7 × age.

Eleven beats is a big number in this context. It means about a third of people sit outside their predicted value ±11, and about one in twenty is more than 22 beats away. Since each zone here is ten percentage points wide (around 18 beats for a typical adult), an eleven-beat prediction error can shift every boundary by more than half a zone. Two people the same age can genuinely need targets a zone apart.

The familiar 220 − age has a worse problem than scatter: it is biased. It comes from a 1971 summary chart by Fox, Naughton and Haskell, was never derived as a regression from pooled data, and its slope is too steep. It over-predicts in young adults and under-predicts in older ones: at 25 it reads 195 against Tanaka's 190.5, and at 65 it reads 155 against Tanaka's 162.5, an error of seven and a half beats in the direction that matters most for older people prescribing themselves training intensity. The two lines happen to cross at exactly age 40, which is why the formula looks fine to middle-aged testers.

What each zone trains and how much time to spend in it

Zones 1 and 2, from 50% to 70% of maximum, are where aerobic base is built: mitochondrial density, capillary supply, fat oxidation and the plain ability to keep going. This work feels almost too easy, which is exactly why it gets skipped. Zone 3, 70–80%, is the comfortably-hard tempo band: productive, but expensive in recovery for the adaptation it buys, and the zone people accidentally live in. Zone 4, 80–90%, is threshold and interval territory that raises the pace you can hold before lactate accumulates. Zone 5, above 90%, is short, sparing work for peak aerobic power.

The pattern that keeps appearing in studies of successful endurance athletes is polarised: roughly 75–80% of training time at low intensity and 20% genuinely hard, with comparatively little in the middle. For a recreational athlete training four or five hours a week, that means three to four hours easy enough to hold a conversation, one or two quality sessions, and the discipline to let the easy days actually be easy. Beginners should spend even more of their time in zones 1 and 2 while tendons, ligaments and habits catch up with the cardiovascular system.

Public health guidance sits below all of this and is worth stating plainly: the WHO recommends 150 to 300 minutes of moderate-intensity activity a week, or 75 to 150 minutes of vigorous activity, plus muscle-strengthening on two days. Moderate corresponds roughly to zones 2 and 3, vigorous to zone 4 and above. If you are training for health rather than performance, hitting that total matters far more than the precise beats-per-minute boundary you hold it at.

Zone 1 (50–60%): warm-up, cool-down, recovery sessions between hard days.
Zone 2 (60–70%): the aerobic base, the majority of weekly training hours for most endurance plans.
Zone 3 (70–80%): tempo work; useful in moderation, easy to overuse.
Zone 4 (80–90%): threshold and intervals; one or two sessions a week for most people.
Zone 5 (90–100%): minutes, not tens of minutes, and only on a well-recovered body.

When perceived exertion or a real test beats the equation

Rating of perceived exertion is free, needs no hardware and correlates well with measured intensity. The talk test is the crude version and works remarkably well: full sentences and comfortable nasal breathing means zones 1 to 2; short sentences only is zone 3; a few words at a time is zone 4; no talking at all is zone 5. If your watch says zone 2 and you cannot finish a sentence, believe your lungs and not the watch. On the 6–20 Borg scale, moderate activity lands around 12 to 13 and vigorous around 14 to 17.

A measured maximum removes the prediction error entirely. A supervised graded exercise test in a laboratory or sports clinic is the reference standard, and is the right route if you have any cardiovascular risk factors. A well-run field test (a long, hard, progressive effort to genuine exhaustion with a chest strap on, taking the highest value reached) will typically get within a few beats of it for a trained person, but it is a maximal effort and carries real risk for anyone unaccustomed to that intensity or with undiagnosed heart disease.

Heart rate also lags and drifts for reasons that have nothing to do with effort. It takes a minute or two to catch up at the start of an interval, so short repetitions end before the number arrives. It climbs several beats over a long session at unchanged pace (cardiac drift), rises in heat and dehydration, and falls when you are cold, well-rested or tapering. Optical wrist sensors lose accuracy badly during rapid changes and for anything involving grip. A chest strap is far more reliable, and for short, sharp work pace or power is a better guide than pulse.

Medications and conditions that invalidate the numbers

Beta blockers are the clearest case. They blunt the heart-rate response to exercise, commonly lowering both resting and maximum rate by twenty to thirty beats per minute, and the effect varies with dose and drug. An age-predicted maximum is simply wrong for someone taking them, and the zones built on it will prescribe efforts that are far harder than intended. The same applies to some calcium-channel blockers, certain antiarrhythmics, and thyroid medication that shifts rate in either direction.

Atrial fibrillation and other arrhythmias make the measurement itself unreliable, since the interval between beats is irregular and most sensors average it badly. A pacemaker with an upper rate limit imposes a ceiling unrelated to your physiology. Some congenital conditions, long-term detraining, spinal cord injury and chronic illness all shift maximum heart rate away from the age-predicted line by more than the equations' own error.

In every one of these cases the answer is the same and it is not a better formula: intensity should be set from perceived exertion, from a walking or cycling test done while on your current medication, or from targets given by a cardiac rehabilitation team. If you have a diagnosed heart condition, take rate-controlling medication, get chest pain, unusual breathlessness or dizziness on exertion, or are returning to exercise after a long gap or an illness, talk to your doctor before working to any maximal or near-maximal target. This page is a reference tool, not medical advice.

How it's calculated

Tanaka, Monahan and Seals (2001): the default here

HRmax = 208 − 0.7 × age (years)

Pooled from 351 studies (18,712 people) plus a 514-person laboratory validation. The regression did not differ between men and women. Standard deviation of individual values around the line: about 10–11 bpm.

Gellish et al. (2007)

HRmax = 207 − 0.7 × age (years)

From 908 graded exercise tests on 132 adults tracked over 25 years, a longitudinal rather than cross-sectional design. Within one beat of Tanaka at every adult age.

Fox, Naughton and Haskell (1971): 220 minus age

HRmax = 220 − age (years)

Shown for comparison only. Not derived as a regression; the slope is too steep, so it over-predicts in young adults and under-predicts after about 40. The two lines cross at exactly age 40, because 208 − 0.7a = 220 − a gives a = 40.

Percentage of maximum zones (ACSM scheme)

Target = HRmax × intensity% · Zones at 50–60, 60–70, 70–80, 80–90 and 90–100%

The simple method. Ignores resting heart rate, so it gives the same targets to a beginner and an athlete of the same age.

Karvonen (1957): heart-rate reserve

Target = ((HRmax − HRrest) × intensity%) + HRrest · Reserve = HRmax − HRrest

Scales only the working range above rest, so it adapts to the individual. Always gives a higher target than the percentage-of-maximum method at the same nominal intensity.

Worked example: a 40-year-old with a resting pulse of 58

Estimate the maximum with Tanaka: 208 − 0.7 × 40 = 208 − 28 = 180 bpm.
Attach the error band: the standard deviation is about 11 bpm, so roughly two 40-year-olds in three have a true maximum between 169 and 191 bpm, and one in twenty is outside 158–202.
Zone 2 as a percentage of maximum: 0.60 × 180 = 108 and 0.70 × 180 = 126, so 108–126 bpm.
Heart-rate reserve: 180 − 58 = 122 bpm of working range.
The same zone 2 by Karvonen: (122 × 0.60) + 58 = 73.2 + 58 = 131 bpm, and (122 × 0.70) + 58 = 85.4 + 58 = 143 bpm, so 131–143 bpm.
Notice the gap: 143 against 126 at the top of zone 2 is seventeen beats, more than most people's week-to-week variation, and the reason to pick one method and stay with it.
Cross-check the equations: 220 − 40 = 180, identical to Tanaka here because the two lines cross at exactly age 40. At 25 the same formula reads 195 against Tanaka's 190.5, and at 65 it reads 155 against 162.5.

Where this number is used in the real world

Structuring an endurance training week, so that easy sessions have a ceiling and hard sessions have a floor instead of everything blurring into the middle.
Cardiac rehabilitation and clinical exercise prescription, where the Karvonen heart-rate reserve method is the long-standing standard for setting safe, individualised targets.
Public health guidance, where moderate and vigorous intensity are defined as bands of maximum heart rate and used to interpret the WHO's weekly activity targets.
Setting up the zones on a sports watch or bike computer, which will otherwise default to 220 − age and quietly misplace every boundary.
Group fitness and personal training, where an instructor needs defensible intensity targets for a room of people whose maximums have never been measured.
Tracking aerobic fitness over months through resting heart rate and heart-rate reserve, both of which move in the right direction as conditioning improves.
Teaching pacing to beginners, by pairing a number on a screen with the talk test so the two calibrate each other.

Frequently asked questions

How accurate is 220 minus age?

Poor, and biased rather than merely noisy. It was never derived as a regression from pooled data; it comes from a 1971 summary chart and has a slope that is too steep. It over-predicts maximum heart rate in young adults and under-predicts it in older ones, by seven or eight beats per minute at age 65. Tanaka's 208 − 0.7 × age fits the pooled evidence far better, though it still carries an individual standard deviation of about eleven beats. Both lines cross at exactly age 40, which is why the old formula looks acceptable to middle-aged testers and fails everyone else.

Should I use percentage of maximum or the Karvonen method?

Either is defensible; what matters is not mixing them. Karvonen uses your heart-rate reserve, the range between resting and maximum, so it adapts to the individual and is the method used in cardiac rehabilitation and by most coaches. Percentage of maximum is simpler and is what most watches use by default. For the same nominal intensity Karvonen always returns a higher target, around seventeen beats higher at the top of zone 2 for a typical adult. If your watch and your coach disagree, this is usually why, and you should settle on one method before judging whether a session was easy enough.

Why is my measured maximum heart rate different from the prediction?

Because the prediction is a population average and individuals scatter widely around it. The standard deviation of true maximum heart rate around any age-based equation is roughly eleven beats per minute, so about a third of people fall outside the predicted value plus or minus eleven, and one in twenty is more than twenty-two beats away. Genetics accounts for most of that spread. Training barely changes your maximum at all: it lowers your resting rate and raises the pace you can sustain, but the ceiling is largely fixed and declines slowly with age regardless of fitness.

Can I use these zones if I take beta blockers?

No. Beta blockers blunt the heart-rate response to exercise, typically lowering both resting and maximum heart rate by twenty to thirty beats per minute depending on the drug and dose, so an age-predicted maximum is simply the wrong number and every zone built from it will ask for a harder effort than intended. The same caution applies to some calcium-channel blockers, certain antiarrhythmics and pacemakers with an upper rate limit. Set intensity from perceived exertion or from a supervised test carried out while on your current medication, and follow the targets your cardiac team gives you.

How much time should I spend in each zone?

For most endurance training the pattern that keeps appearing in studies of successful athletes is polarised: roughly three-quarters to four-fifths of total time at low intensity in zones 1 and 2, around a fifth genuinely hard in zones 4 and 5, and comparatively little in the middle. For someone training four or five hours a week that means three to four easy hours plus one or two quality sessions. Beginners should skew further towards the easy end while connective tissue adapts. For general health rather than performance, the weekly total of moderate or vigorous minutes matters much more than the exact split.

Is a lower resting heart rate always better?

Lower usually reflects better aerobic conditioning, because a stronger heart moves more blood per beat and so needs fewer beats at rest, but the comparison that means anything is with your own previous readings rather than with other people. Healthy adults vary by twenty beats or more at the same level of fitness. A resting rate that climbs five beats and stays there for several days generally signals illness, poor sleep, dehydration or too much training. An unusually low rate accompanied by dizziness, fainting or breathlessness is worth a medical opinion rather than a calculator.

Do heart rate zones differ for men and women?

Not in the equations used here. The Tanaka regression was explicitly reported as independent of sex (men and women of the same age have statistically indistinguishable predicted maximums) and the zone percentages are applied identically. Where sex does show up is indirectly, through resting heart rate and heart-rate reserve, which is another argument for the Karvonen method if you want targets that reflect the individual. Some later work suggests women's maximums decline slightly more slowly with age, but the effect is small compared with the eleven-beat individual scatter around any prediction.

Why does my heart rate keep rising even though my pace is steady?

That is cardiac drift, and it is normal. Over a long session at unchanged effort the heart rate climbs several beats as plasma volume falls through sweating, core temperature rises and stroke volume drops slightly, so the heart compensates with frequency. Heat, dehydration, caffeine and altitude all exaggerate it. It means a heart rate cap becomes progressively more restrictive as a long session goes on, which is one reason runners and cyclists often pace long efforts by pace or power and use heart rate as a check rather than as the controlling variable.

Keep going

A single number rarely tells the whole story. Alongside the heart rate zones result, the TDEE calculator, the BMR calculator, the body fat calculator and the water calculator each add a different angle on the same measurements. For the reasoning behind the numbers, read TDEE explained, BMI for athletes and Track without DEXA.

Sources

Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 2001;37(1):153–6. doi.org/10.1016/S0735-1097(00)01054-8
Gellish RL, Goslin BR, Olson RE, McDonald A, Russi GD, Moudgil VK. Longitudinal modeling of the relationship between age and maximal heart rate. Med Sci Sports Exerc 2007;39(5):822–9. doi.org/10.1097/mss.0b013e31803349c6
Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Ann Med Exp Biol Fenn 1957;35(3):307–15. pubmed.ncbi.nlm.nih.gov/13470504/
Fox SM 3rd, Naughton JP, Haskell WL. Physical activity and the prevention of coronary heart disease. Ann Clin Res 1971;3(6):404–32, the origin of 220 minus age. pubmed.ncbi.nlm.nih.gov/4945367/
American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription, the source of the percentage-of-maximum and heart-rate-reserve intensity classifications. acsm.org/education-resources/books/guidelines-exercise-testing-prescription/
World Health Organization. WHO guidelines on physical activity and sedentary behaviour. Geneva, 2020. www.who.int/publications/i/item/9789240015128

Cite this page

Quoting a figure from here in an article, a report or a piece of coursework? Use whichever of these your style guide asks for.

APA: Campbell, R. (2026). Heart rate zone calculator. Body Stats. https://bodystats.co/app/heart-rate-zone-calculator
Plain text: “Heart rate zone calculator”, Body Stats, last updated 12 September 2026, https://bodystats.co/app/heart-rate-zone-calculator

Every formula and threshold on this page is written out with its primary source on our methodology page. These results are informational and educational, not a diagnosis or a substitute for professional advice. See the medical disclaimer.

Last updated 12 September 2026. Written by Rick Campbell; not medically reviewed. See review status.