Max Heart Rate by Age: The Zone Chart, and Why 220 − Age Is Wrong

For a 40-year-old, the best available estimate of maximum heart rate is about 180 bpm — 208 − (0.7 × 40) — not the 180 you get from 220 − age by coincidence. At 60 the two formulas disagree by six beats. At 80 they disagree by twelve.¹

And the estimate that wins on average is still wrong for you specifically. The largest single-lab dataset on this question, 3,320 healthy adults in Norway’s HUNT Fitness Study, put the standard error of any age-based prediction at 10.8 beats per minute.² Roughly one person in three sits more than 11 bpm from the formula. One in twenty sits more than 21 bpm away.

Here’s the part that matters more than either number: even a perfectly measured max heart rate does not fix your training zones. When researchers at the University of Calgary measured where the lactate threshold actually falls in 100 people, it landed anywhere between 60% and 90% of maximum heart rate.³ That range spans three of the five zones your watch draws. For one person, “Zone 2” is easy aerobic work. For another, the same percentage is already over the line.

Your watch hands you a zone chart with the confidence of a lab result. It’s a population average wearing a lab coat — and closing the gap between that average and your actual physiology is exactly what SensAI was built to do.

What is a normal max heart rate for my age?

Maximum heart rate (HRmax) is the highest rate your heart can beat during all-out effort. It is set largely by age and, unlike almost every other fitness number, it does not improve with training. Tanaka’s meta-analysis of 351 studies covering 18,712 people found HRmax was unrelated to habitual physical activity and did not differ between men and women.¹ A fitter heart pumps more blood per beat; it does not gain a higher ceiling.

Three formulas are worth knowing. Here is what each predicts by decade:

Age	220 − age (legacy)	Tanaka: 208 − 0.7 × age	HUNT: 211 − 0.64 × age
20	200	194	198
30	190	187	192
40	180	180	185
50	170	173	179
60	160	166	173
70	150	159	166
80	140	152	160

Notice the pattern. The three agree around age 40 and diverge steadily after it. By 70, the legacy formula is nine beats low against Tanaka and sixteen low against HUNT.

That direction of error is not random. Both research groups reached the same conclusion independently: 220 − age systematically underestimates maximum heart rate in older adults.¹² For anyone over 50, using it means training and testing at a lower true intensity than intended — the opposite of the cautious error most people assume they’re making.

Where did 220 − age come from?

Not from a study designed to answer the question.

The equation traces to a 1971 review by Fox, Naughton, and Haskell on physical activity and coronary heart disease prevention.⁴ It was a line fitted through mixed data drawn from earlier work, offered as a rough clinical convenience — never a validated regression from a controlled experiment.

It spread anyway, because it is trivially easy to do in your head. Fifty years later it is still the default in most consumer watches and most gym cardio equipment.

Hirofumi Tanaka and colleagues at the University of Colorado Boulder set out to fix it properly in 2001. They pooled group means from 351 studies, derived HRmax = 208 − 0.7 × age, then cross-validated it in a separate laboratory sample of 514 healthy people. The lab-derived equation came back as 209 − 0.7 × age — essentially identical.¹ Gellish and colleagues later followed adults longitudinally over multiple exercise tests and landed at 207 − 0.7 × age, converging on the same slope from a different design.⁵

Bjarne Nes, Ulrik Wisløff, and colleagues at the K.G. Jebsen Center of Exercise in Medicine in Trondheim then ran the largest single-sample test: 3,320 healthy adults, all with a verified maximal effort, producing 211 − 0.64 × age.² Like Tanaka, they found no meaningful interaction with sex, BMI, physical activity status, or VO₂max.

Three independent methods. Three slopes near 0.7. And one number none of them could shrink: the individual error bar.

Heart rate zones by age: the standard chart

The five-zone model most watches use divides the range as a percentage of HRmax. Using Tanaka’s estimate, here is the full chart by decade:

Age (HRmax)	Zone 1 (50–60%)	Zone 2 (60–70%)	Zone 3 (70–80%)	Zone 4 (80–90%)	Zone 5 (90–100%)
20 (194)	97–116	116–136	136–155	155–175	175–194
30 (187)	94–112	112–131	131–150	150–168	168–187
40 (180)	90–108	108–126	126–144	144–162	162–180
50 (173)	87–104	104–121	121–138	138–156	156–173
60 (166)	83–100	100–116	116–133	133–149	149–166
70 (159)	80–95	95–111	111–127	127–143	143–159

Use this the way you would use a shoe size chart: a starting point that fits most people approximately and nobody exactly.

There is a second method worth knowing, because it fixes one real flaw. The Karvonen formula works from heart rate reserve — the gap between your resting and maximum rates — rather than from HRmax alone:⁶

Target = ((HRmax − resting HR) × intensity %) + resting HR

The difference is not cosmetic. A 40-year-old with a resting heart rate of 55 gets a 60% target of 108 bpm from the straight percentage method, but 130 bpm from Karvonen. That is the distance between a warm-up and actual aerobic work. Because Karvonen incorporates your resting heart rate, it partially accounts for your fitness — which is why it’s the better of the two arithmetic options, and why your resting heart rate by age is worth tracking as a companion number.

Why the zone chart is wrong for you specifically

Both formulas share a hidden assumption: that the physiological boundaries between easy, moderate, and hard sit at fixed percentages for everyone. They don’t.

Danilo Iannetta, Juan M. Murias, and colleagues at the University of Calgary tested this directly in 100 people (46 women, 54 men). Each completed a ramp test to exhaustion plus 30-minute constant-work-rate trials to pin down the lactate threshold and the maximal lactate steady state — the two boundaries that genuinely separate the moderate, heavy, and severe exercise domains.

Then they asked where those boundaries fell as a percentage of each person’s own maximum:³

Physiological boundary	Range across 100 people
Lactate threshold	60–90% of HRmax
Maximal lactate steady state	75–97% of HRmax

Read that against the zone chart above. For a 40-year-old with a 180 bpm max, the lactate threshold could sit at 108 bpm or at 162 bpm depending on who they are. The chart calls the first Zone 2 and the second Zone 4.

The authors’ conclusion is blunt: prescriptions based on fixed percentages of maximal values “conform poorly to exercise intensity domains and thus do not adequately control the metabolic stimulus.”³ Two people following the identical zone prescription can be doing genuinely different workouts.

This is not a rounding error, and it shows up in results. Weatherwax and colleagues randomized 39 sedentary adults to twelve weeks of identical training volume, differing only in how intensity was set — standard heart-rate-reserve percentages versus individual ventilatory thresholds. Both groups improved. But 100% of the threshold-anchored group were classified as VO₂max responders, against 60% of the percentage-anchored group.⁷

Four people in ten trained for three months and got no measurable cardiorespiratory return, for no reason other than how their zones were drawn. Meyler and colleagues’ review of VO₂max response variability reaches the same place from the literature side: how intensity is prescribed is itself a driver of who responds.⁸

How to find your real threshold in one session

You do not need a lab. You need one honest 20–30 minute effort and the willingness to pay attention.

Carl Foster’s group at the University of Wisconsin–La Crosse and colleagues in Zagreb reviewed the validity of subjective intensity anchors and found the Talk Test and RPE to be valid markers of both the ventilatory threshold and the respiratory compensation threshold — the practical stand-ins for the two boundaries Iannetta measured.⁹

The calibration:

What you can do while moving	Boundary it marks	Borg RPE (6–20)
Speak comfortably in full sentences	Below the first threshold — true easy aerobic	~9–10
Speech becomes strained, phrases shorten (“equivocal”)	Ventilatory threshold — the top of easy	10–11
Speech breaks to a few words at a time (“negative”)	Respiratory compensation threshold — the top of sustainable	13–15

Run this protocol once:

1. Warm up 10 minutes easy.
2. Increase effort in small steps every 3 minutes — a bit faster, a bit steeper, a bit more watts.
3. At the end of each step, recite two full sentences out loud.
4. Note the heart rate at the step where speech first turns strained. That is the top of your Zone 2, not 70% of anything.
5. Continue to where you can only manage a few words. Note that heart rate too — that is the top of your sustainable range.
6. Cool down.

Now rebuild your zones around those two measured numbers instead of around a percentage. Everything below the first is easy work. Everything between the two is threshold work. Everything above the second is where intervals live.

Re-test every eight to twelve weeks. Both thresholds move with fitness — unlike HRmax, which barely moves at all. That is the whole point: you are calibrating to the numbers that actually change. Our Zone 2 without 220 − age guide walks the same calibration in more detail for endurance work specifically.

Does the fat burning zone exist?

Yes — and it is far less useful than the label implies.

There is a real intensity at which fat oxidation peaks, called FATmax. A systematic review and meta-regression by Isaac Chávez-Guevara and colleagues, pooling 64 studies, located it and made one methodological finding directly relevant here: heart rate is a better anchor for it than oxygen uptake, with an intra-individual coefficient of variation of 8.8% versus 17.2%.¹⁰

Where it falls:

Body fat	Heart rate at peak fat oxidation
Under 35%	57–64% of peak HR
Over 35%	61–66% of peak HR

So the zone is real, it is roughly the low end of Zone 2, and it shifts with body composition. What it is not is the fastest route to fat loss. Peak fat oxidation rate in these studies ran 0.27–0.33 grams per minute — about 15 to 20 grams of fat per hour of exercise.¹⁰ Higher intensities burn a smaller fraction of energy from fat but far more total energy, and body composition follows total energy balance rather than substrate mix. If your goal is fat loss, the fat burning zone is a physiological curiosity, not a strategy — and your watch’s calorie burn estimate is a weaker number than its heart rate reading anyway.

Your watch’s heart rate is not a chest strap’s

Zone math is only as good as the input. Wrist optical sensors are meaningfully less accurate than the electrical measurement a chest strap makes.

Schweizer and Gilgen-Ammann at the Swiss Federal Institute of Sport Magglingen validated PPG devices against an ECG chest strap across nine activities from lying down through high-intensity intervals:¹¹

Device and position	Mean absolute error	MAPE
Armband (upper arm)	1.43 bpm	1.35%
Watch (non-dominant wrist)	6.41 bpm	6.82%

A 6.8% error on a 150 bpm reading is about ±10 bpm — roughly one full zone at most ages on the chart above. Earlier work by Dooley and colleagues at the University of Texas at Austin, testing three consumer wrist devices against a chest strap in 62 people, found the same spread and showed it is device-dependent: heart rate MAPE ranged from 1.14–6.70% for one watch to 7.87–24.38% for another, with accuracy varying by exercise intensity within each device.¹²

Two practical rules follow. Wear the watch snug and above the wrist bone, because fit drives most of the error. And for interval work specifically — where heart rate changes faster than an optical sensor can track it — use a chest strap or an armband if the zone actually matters. If you’re weighing which device to buy, our wearable accuracy comparison covers how the major platforms differ.

When heart rate lies about intensity

Even a perfect reading from a perfect device can misrepresent how hard you are working.

The clearest case is cardiovascular drift. Wingo and colleagues showed that during prolonged exercise, especially in heat, heart rate climbs over time at an unchanged work rate while stroke volume falls — and VO₂max itself declines in parallel.¹³ Ninety minutes in, your heart rate says Zone 3 and your legs are doing Zone 2 work. Holding a heart rate target under those conditions means unknowingly reducing your actual training stimulus.

It compounds in the heat. A 2025 study from the same group found that maintaining a target heart rate and RPE during high-intensity intervals in hot conditions required progressively reducing work rate across the session.¹⁴ Same effort by the number, less work performed.

Sleep debt, illness, dehydration, caffeine, and alcohol all shift resting and submaximal heart rate independently of fitness. This is where a single-session zone read fails and a longitudinal one succeeds: SensAI reads today’s heart rate against your own multi-week baseline and your recovery signals, so a 10 bpm elevation gets interpreted as the drift, the heat, or the poor night that caused it — not silently converted into a false claim about your fitness. The same logic applies to aerobic decoupling, which turns drift from a nuisance into a usable fitness signal.

How much time should you spend in each zone?

This is where the honest answer is less prescriptive than the internet suggests.

Rosenblat and 16 co-authors — including Stephen Seiler, the researcher most associated with the polarized model — ran a network meta-analysis of individual participant data from 13 studies and 348 endurance athletes, comparing training intensity distributions head to head. Using the time-in-heart-rate-zone approach, polarized and pyramidal distributions produced no significant difference in VO₂max (SMD = −0.06, p = 0.68) or time-trial performance (SMD = −0.05, p = 0.34).¹⁵

The one signal that did emerge was a split by training status: competitive athletes tended to respond better to polarized distribution, recreational athletes to pyramidal — a statistically significant difference between the two groups (SMD = −0.63, p < 0.05).¹⁵

The practical reading: if you are a recreational athlete, the popular “80/20 polarized or nothing” prescription is not supported over a pyramidal alternative for you. What is well supported across every distribution studied is that most of your volume sits below the first threshold and a minority sits meaningfully above it. Our HIIT versus Zone 2 breakdown and the full intensity-distribution comparison go deeper on how to actually split a week.

How SensAI uses your heart rate zones

Everything above is a calibration problem stretched over months, and calibration problems are where good intentions quietly fail.

Your watch set your zones from 220 − age on the day you unboxed it and has not revisited the question since. Your thresholds have moved. Your resting heart rate has moved. Your maximum, in all likelihood, has not — but you have never actually measured it, so the whole chart rests on an estimate carrying ±11 bpm of error.²

SensAI reads the numbers already in HealthKit — every session’s heart rate curve, your resting trend, your recovery signals from Apple Watch, Garmin, Oura, or WHOOP — and holds them against each other over time. When your heart rate at a familiar pace drops over six weeks, that is a threshold that has moved and zones that need redrawing. When it climbs on a day your sleep and HRV are both down, that is context, not fitness loss.

Tell the coach what your talk test returned and it remembers — the AI memory system carries constraints and results across sessions, so your measured thresholds stay attached to your training rather than living in a note you lost in March. And when you ask why today’s session is capped at a specific heart rate, you get the reasoning, not a score.

Not a formula from 1971. Your own two thresholds, re-measured as they move, and the training decision that follows from them.

Frequently asked questions

What is a good max heart rate for my age?

There is no “good” or “bad” HRmax — it is a ceiling set by age and genetics, not a fitness marker.¹ The best age-based estimate is 208 − (0.7 × age): about 194 at 20, 180 at 40, 166 at 60, and 152 at 80.

Is 220 minus your age accurate?

No. It originated in a 1971 clinical review rather than a validated study,⁴ and it systematically underestimates maximum heart rate in adults over 50 — by roughly nine beats at age 70 against Tanaka’s equation and sixteen against the HUNT equation.¹²

What is the most accurate max heart rate formula?

Tanaka’s 208 − 0.7 × age and the HUNT study’s 211 − 0.64 × age are the best-validated.¹² Both still carry a standard error near 10.8 bpm for any individual,² so a measured maximum from an all-out test always beats a formula.

What are my heart rate zones by age?

Using Tanaka’s estimate, a 40-year-old’s five zones are roughly 90–108, 108–126, 126–144, 144–162, and 162–180 bpm. See the full chart by decade above — but treat it as a starting point, since the lactate threshold falls anywhere from 60% to 90% of HRmax across individuals.³

What is Zone 2 heart rate by age?

By the standard 60–70% model: about 116–136 bpm at 20, 108–126 at 40, and 100–116 at 60. Your true Zone 2 ceiling is the heart rate where you can no longer speak in full sentences, which is measurable in one session and is the number worth using.⁹

How do I find my actual max heart rate?

A supervised maximal graded exercise test is the gold standard. Field alternatives exist — a fully warmed-up all-out effort on a hill or track, taking the highest reading — but they carry real cardiovascular risk if you have any risk factors or are new to hard training. Get medical clearance first. For most people, calibrating to threshold matters more than knowing HRmax exactly.

Does your max heart rate go down as you get fitter?

No. Training does not change your maximum heart rate.¹ What changes is everything else: your resting heart rate falls, your stroke volume rises, and the pace or power you can hold at any given heart rate improves.

Is the fat burning zone real?

The intensity of peak fat oxidation is real and sits at roughly 57–66% of peak heart rate depending on body composition.¹⁰ But peak fat oxidation runs only 0.27–0.33 g/min, and fat loss follows total energy balance rather than which fuel you burned during the session.

Why is my watch’s heart rate different from my chest strap?

Wrist optical sensors measure blood volume changes through skin and are disturbed by motion, fit, and skin perfusion. A validation study found a wrist device’s mean absolute error at 6.41 bpm against ECG, versus 1.43 bpm for the same technology worn on the upper arm.¹¹

Why is my heart rate higher for the same effort some days?

Heat, dehydration, sleep debt, illness, caffeine, alcohol, and cardiovascular drift within a long session all raise heart rate at an unchanged work rate.¹³¹⁴ A single day’s reading tells you very little; the trend against your own baseline tells you a lot.

The bottom line

220 − age was never a research result. It was a convenient line through mixed data in a 1971 review,⁴ and it underestimates maximum heart rate in older adults.¹² Use 208 − (0.7 × age) if you want an arithmetic answer, and use Karvonen if you know your resting heart rate.

But do not mistake a better formula for a solved problem. The error bar on any age-based prediction is about 11 bpm,² and the deeper issue is that the boundaries your zones are meant to represent land anywhere between 60% and 90% of maximum depending on the person.³

That is not a technicality. Anchoring to measured thresholds instead of percentages turned a 60% responder rate into 100% over twelve weeks of otherwise identical training.⁷

So run the talk test once. Find the heart rate where full sentences break, and the one where speech drops to a few words. Build your zones from those two numbers, re-test them every couple of months, and let the formula go.

Your watch gave you a population average. You can measure the real thing in half an hour.

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References

Footnotes

1. Tanaka H, Monahan KD, Seals DR. “Age-predicted maximal heart rate revisited.” Journal of the American College of Cardiology, 2001;37(1):153-156. https://pubmed.ncbi.nlm.nih.gov/11153730/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

2. Nes BM, Janszky I, Wisløff U, Støylen A, Karlsen T. “Age-predicted maximal heart rate in healthy subjects: The HUNT fitness study.” Scandinavian Journal of Medicine & Science in Sports, 2013;23(6):697-704. https://pubmed.ncbi.nlm.nih.gov/22376273/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

3. Iannetta D, Inglis EC, Mattu AT, Fontana FY, Pogliaghi S, Keir DA, Murias JM. “A Critical Evaluation of Current Methods for Exercise Prescription in Women and Men.” Medicine and Science in Sports and Exercise, 2020;52(2):466-473. https://pubmed.ncbi.nlm.nih.gov/31479001/ ↩ ↩² ↩³ ↩⁴ ↩⁵

4. Fox SM 3rd, Naughton JP, Haskell WL. “Physical activity and the prevention of coronary heart disease.” Annals of Clinical Research, 1971;3(6):404-432. https://pubmed.ncbi.nlm.nih.gov/4945367/ ↩ ↩² ↩³

5. Gellish RL, Goslin BR, Olson RE, McDonald A, Russi GD, Moudgil VK. “Longitudinal modeling of the relationship between age and maximal heart rate.” Medicine and Science in Sports and Exercise, 2007;39(5):822-829. https://pubmed.ncbi.nlm.nih.gov/17468581/ ↩

6. Karvonen MJ, Kentala E, Mustala O. “The effects of training on heart rate; a longitudinal study.” Annales Medicinae Experimentalis et Biologiae Fenniae, 1957;35(3):307-315. https://pubmed.ncbi.nlm.nih.gov/13470504/ ↩

7. Weatherwax RM, Harris NK, Kilding AE, Dalleck LC. “Incidence of V̇O2max Responders to Personalized versus Standardized Exercise Prescription.” Medicine and Science in Sports and Exercise, 2019;51(4):681-691. https://pubmed.ncbi.nlm.nih.gov/30673687/ ↩ ↩²

8. Meyler S, Bottoms L, Muniz-Pumares D. “Biological and methodological factors affecting V̇O2max response variability to endurance training and the influence of exercise intensity prescription.” Experimental Physiology, 2021;106(7):1410-1424. https://pubmed.ncbi.nlm.nih.gov/34036650/ ↩

9. Bok D, Rakovac M, Foster C. “An Examination and Critique of Subjective Methods to Determine Exercise Intensity: The Talk Test, Feeling Scale, and Rating of Perceived Exertion.” Sports Medicine, 2022;52(9):2085-2109. https://pubmed.ncbi.nlm.nih.gov/35507232/ ↩ ↩²

10. Chávez-Guevara IA, Amaro-Gahete FJ, Ramos-Jiménez A, Brun JF. “Toward Exercise Guidelines for Optimizing Fat Oxidation During Exercise in Obesity: A Systematic Review and Meta-Regression.” Sports Medicine, 2023;53(12):2399-2416. https://pubmed.ncbi.nlm.nih.gov/37584843/ ↩ ↩² ↩³

11. Schweizer T, Gilgen-Ammann R. “Wrist-Worn and Arm-Worn Wearables for Monitoring Heart Rate During Sedentary and Light-to-Vigorous Physical Activities: Device Validation Study.” JMIR Cardio, 2025;9:e67110. https://pubmed.ncbi.nlm.nih.gov/40116771/ ↩ ↩²

12. Dooley EE, Golaszewski NM, Bartholomew JB. “Estimating Accuracy at Exercise Intensities: A Comparative Study of Self-Monitoring Heart Rate and Physical Activity Wearable Devices.” JMIR mHealth and uHealth, 2017;5(3):e34. https://pubmed.ncbi.nlm.nih.gov/28302596/ ↩

13. Wingo JE, Ganio MS, Cureton KJ. “Cardiovascular drift during heat stress: implications for exercise prescription.” Exercise and Sport Sciences Reviews, 2012;40(2):88-94. https://pubmed.ncbi.nlm.nih.gov/22410803/ ↩ ↩²

14. Yoder HA, Mulholland AM, MacDonald HV, Wingo JE. “Work rate adjustments needed to maintain heart rate and RPE during high-intensity interval training in the heat.” Frontiers in Physiology, 2025;16:1506325. https://pubmed.ncbi.nlm.nih.gov/39981303/ ↩ ↩²

15. Rosenblat MA, Watt JA, Arnold JI, Treff G, Sandbakk ØB, Esteve-Lanao J, Festa L, Filipas L, Galloway SD, Muñoz I, Ramos-Campo DJ, Schneeweiss P, Sellés-Pérez S, Stöggl T, Talsnes RK, Zinner C, Seiler S. “Which Training Intensity Distribution Intervention will Produce the Greatest Improvements in Maximal Oxygen Uptake and Time-Trial Performance in Endurance Athletes? A Systematic Review and Network Meta-analysis of Individual Participant Data.” Sports Medicine, 2025;55(3):655-673. https://pubmed.ncbi.nlm.nih.gov/39888556/ ↩ ↩²