How Every Watch Calculates Your Max Heart Rate (10 Brands Compared)
Every heart rate zone you have ever trained in was drawn from a number your watch guessed. The brands do not guess the same way, they do not agree on what the zones are percentages of, and most of them do not tell you which method they use.
Here is all of it in one place.
| Brand | HRmax estimate | Zones anchored to | Updates itself | You can set it |
|---|---|---|---|---|
| Garmin | Tanaka, 208 − 0.7 × age | %HRmax | Yes, raises from recorded peaks | Yes, per sport on higher tiers |
| COROS | Gellish, 207 − 0.7 × age | Your choice of threshold, reserve or %HRmax | Only via the Running Fitness Test | Yes |
| Polar | 220 − age | %HRmax, 10-point bands | No | Yes, per sport profile |
| Suunto | 220 − age | %HRmax, 5-point bands | No | Yes |
| Apple Watch | Unpublished, age required | Stated as %HRmax, community says reserve | Yes, from health data | No HRmax field, only zone limits |
| Fitbit | 220 − age | Heart rate reserve | No | Yes, custom max |
| Samsung | 220 − age, or Galaxy AI zones | %HRmax | Optional automatic zones | Yes, per exercise type |
| WHOOP | Gellish seed, then learned | %HRmax, drives Strain | Yes, from 24/7 data | Yes |
| Wahoo | Tanaka, then 88% of it as threshold | Threshold heart rate | No | Yes, set THR |
| Strava | 220 − age, or 190 with no age | %HRmax | Yes, every birthday | Yes |
Four things that table tells you
Half the industry is still on a formula from 1971. 220 − age was never derived from research. It carries an individual error of roughly ±10 to 12 bpm and is biased, too high for the young and too low for the old. At 20 it says 200 where Gellish says 193. At 60 it says 160 where Gellish says 165. Garmin, COROS, WHOOP and Wahoo have all moved off it. Polar, Suunto, Fitbit, Samsung and Strava have not.
The formula matters less than what the zones are percentages of. Tanaka and Gellish differ by exactly one beat at every age, which is nothing. But a zone placed inside your heart rate reserve sits much higher in bpm than the same percentage of your maximum. That is a real difference of ten beats or more at the same nominal zone, and it is why your Fitbit and your Garmin disagree about the same run.
Auto-detection is not the upgrade it sounds like. Garmin, WHOOP, Apple and Samsung all adjust your maximum from recorded data. A learned number can only ever move up, and optical wrist sensors throw artefact spikes at exactly the intensities where the model is watching. One bad reading installs a maximum you never reached, and it stays.
Two of them are not percentage-of-maximum systems at all. Wahoo anchors to threshold heart rate. COROS offers threshold as one of three models and, whichever you pick for display, analyses your training with the threshold zones anyway.
Recommended HRmax
184bpm
Tanaka (2001)
Average of all 6 models
183bpm
if unsure, use this
Six published predictors, side by side (±10–12 bpm typical error)
| Fox / Haskell (1971) | 185 bpm |
| Tanaka (2001)Recommended | 184 bpm |
| Gellish (2007) | 183 bpm |
| Nes (2013) | 189 bpm |
| Gulati, women (2010) | 175 bpm |
| Londeree & Moeschberger | 181 bpm |
| Average of all six modelsmean of the predictors above | 183 bpm |
- We recommend Tanaka (2001) because it was re-derived from a meta-analysis of 18,712 people and is more accurate across ages than the old 220 minus age rule, which tends to run high for older athletes.
- Formula-predicted HRmax carries a standard deviation of roughly ±10–12 bpm, so two athletes of the same age can differ by 20+ bpm. Use it as a starting point only.
- For accuracy, do a maximal field test (e.g. a hard hill-repeat session or a supervised ramp test) and read your true HRmax from the device.
A PDF of your personalized results, with a QR code to reopen them anytime.
Compare the formulas on your own age and you will see the spread the defaults hide.
What to actually do
- Test your maximum rather than accepting a formula. Build to hard over 10 to 15 minutes, finish with an all-out 60 to 90 second effort, take the highest reading off a chest strap, repeat within two weeks and keep the higher number. Not for anyone with cardiac risk or new to hard training. Protocol in finding your maximum heart rate.
- Enter it everywhere, including Strava, which re-buckets your uploaded data with its own setting.
- Turn off auto-detection where the brand allows it, so a sensor spike cannot overwrite a tested number.
- Move to a better anchor if you can. Threshold heart rate rises with fitness where maximum falls with age. LTHR zones is the model, and LTHR vs %HRmax zones explains why the two systems place Zone 2 differently. Karvonen is the middle option if you know your resting heart rate but not your threshold.
FAQ
Which watch brand has the most accurate max heart rate? None of them measure it. Garmin, COROS and WHOOP use better age formulas than 220 − age, and WHOOP and Garmin adjust from your data, but a tested value entered by hand beats every default.
Why do my Garmin and Strava zones differ? They hold separate max heart rate settings and apply them to the same data. Fix both.
Is 220 minus age wrong? It is a population average with roughly ±10 to 12 bpm of individual error, and it is systematically off at both ends of the age range. Tanaka's 208 − 0.7 × age and Gellish's 207 − 0.7 × age are better, but only by fixing the bias, not the scatter.
Which brands let me set max heart rate per sport? Garmin on its higher tiers, Polar through sport profiles, and Samsung per exercise type. It is worth using, because running maximums usually sit several beats above cycling maximums.
Does a higher max heart rate mean I am fitter? No. It is a largely genetic ceiling that falls with age regardless of training. Fitness is how much of it you can use and for how long.
VO2 max by brand
The same exercise, one number further down the chain, is covered per brand too: Garmin, Apple Watch, COROS, Polar, Fitbit, WHOOP and Suunto. Every one of those estimates is built on the max heart rate in the table above, which is the reason to get it right.
Sources
- Garmin, COROS, Polar, Suunto, Apple Watch, Fitbit, Samsung, WHOOP, Wahoo and Strava, each with its own first-party sources.
- Tanaka, Monahan & Seals (2001), the 208 − 0.7 × age formula
- Gellish et al. (2007), the 207 − 0.7 × age formula
- Karvonen, Kentala & Mustala (1957), the heart rate reserve method
Cover photo by ArnoldReinhold, CC BY-SA 4.0, via Wikimedia Commons.
