How COROS Calculates Your Max Heart Rate (HRmax)

COROS does not measure your maximum heart rate (HRmax). It uses the value in your profile, and the formula it tells you to estimate that value with is 207 − 0.7 × age, the Gellish formula. That is not the one Garmin uses, and it is not 220 − age. There is a second thing almost nobody knows: whichever zone model you choose, EvoLab analyses your training with the lactate-threshold zones regardless.

The formula COROS recommends

COROS's own heart rate zone guide says 220 − age carries a standard deviation of about ±12 beats and recommends 207 − 0.7 × age instead. For a 40-year-old that is 207 − 28 = 179 bpm.

COROS's 207 − 0.7 × age and Garmin's Tanaka 208 − 0.7 × age differ by exactly one beat at every age, so switching brands changes nothing. Both diverge from 220 − age at the ends of the range:

• At 20: 220 − age says 200. COROS says 193.
• At 40: 220 − age says 180. COROS says 179.
• At 60: 220 − age says 160. COROS says 165.

Anyone still carrying a 220 − age estimate is seven beats too high at 20 and five too low at 60, which is why both brands abandoned it.

None of it fixes the underlying problem. Every age formula carries an error of roughly ±10 to 12 bpm for an individual, wide enough to put your zone boundaries in the wrong place.

Three zone models

Most watches give you one zone system. COROS gives you three, each with six zones:

• Lactate threshold. Anchored to threshold heart rate. Zone 1 under 80% of it, zone 2 at 80 to 90%, zone 3 at 90 to 95%, zone 4 at 95 to 102%, zone 5 at 102 to 106%, zone 6 above 106%.
• Heart rate reserve. Anchored to HRmax and resting HR, the Karvonen approach.
• Max heart rate. Anchored to HRmax alone.

Pick the lactate threshold model and your HRmax barely matters for zone display. Pick either of the others and it sets every boundary you see. LTHR vs %HRmax zones covers why the two systems put Zone 2 in different places.

The part nobody tells you about EvoLab

COROS states that EvoLab always uses the default lactate-threshold zones when analysing your training over time, whatever model you selected.

So the zones on your wrist and the zones behind your training load, base fitness and marathon-level numbers can be two different sets. Switching model changed what you look at, not how COROS scores your week.

Standardising the analysis keeps metrics comparable over months. It also means fixing a wrong HRmax will not fix a training load number that looks off, and fixing a wrong threshold heart rate will.

What HRmax drives on a COROS

• Zone boundaries, on the heart rate reserve and max heart rate models.
• Heart rate reserve, the gap between resting and maximum.
• The 65% threshold that unlocks EvoLab. COROS documents that it needs at least one 25-minute run above 65% of heart rate reserve before producing running fitness metrics. An HRmax set too high raises that bar, so a run that should have counted does not.

How to set it manually

In the COROS app: Profile → Settings → Heart Rate Zone, choose your zone type, edit the value.

HRmax and resting HR are yours to set. Enter a tested number and it stays. Threshold heart rate is not. Only the algorithm adjusts that, through the Running Fitness Test, which returns updated threshold pace, threshold heart rate and maximum heart rate together.

That is the opposite of the Garmin problem. Garmin silently raises HRmax on optical sensor spikes, so its users often carry an HRmax a few beats too high. COROS leaves it alone, so a wrong number stays wrong until you fix it.

How to find your real HRmax

Build to hard over 10 to 15 minutes, finish with an all-out 60 to 90 second effort, uphill if you can, and take the highest number off a chest strap rather than the wrist. Repeat within two weeks and keep the higher figure. Not for anyone with cardiac risk or new to hard training. Full protocol in finding your maximum heart rate.

On the heart rate reserve model, pair the result with your resting heart rate in the Karvonen calculator. On the lactate threshold model, LTHR zones is the match.

FAQ

What formula does COROS use for max heart rate? COROS recommends 207 − 0.7 × age, the Gellish formula, not 220 − age. It does not measure HRmax, it uses the value in your profile.

Does COROS update my max heart rate automatically? Not from everyday training the way Garmin does. The Running Fitness Test returns an updated max heart rate alongside threshold pace and threshold heart rate, and you can set it by hand any time.

Why can I not edit my threshold heart rate on COROS? By design. COROS lets you set HRmax and resting HR manually but reserves threshold heart rate for its algorithm.

Does changing my zone model change my training load? No. EvoLab always analyses with the lactate-threshold zones, whichever model you selected.

Which COROS zone model should I use? Lactate threshold if you have a tested threshold heart rate, because it is the anchor EvoLab uses anyway. Heart rate reserve if you do not.

Other brands

• Garmin uses Tanaka and auto-raises HRmax from recorded peaks.
• COROS recommends Gellish and runs three zone models.
• Apple Watch publishes no formula at all.
• Polar, Suunto, Fitbit, Samsung and Strava all default to 220 − age.
• WHOOP learns it from your data. Wahoo skips HRmax and anchors to threshold.

Sources

• COROS heart rate zones guide
• COROS Help Center on setting resting and max heart rate
• COROS Help Center on running fitness metrics
• COROS Help Center on fitness tests
• Gellish et al. (2007), the 207 − 0.7 × age formula
• Tanaka, Monahan & Seals (2001), the 208 − 0.7 × age formula

Cover photo by Motwog, CC BY 4.0, via Wikimedia Commons.