Watches and tests

Is Garmin VO2 max accurate?

By GyroscopeUpdated November 14, 20267 sources

Close for most people, and less certain for elite endurance athletes. A Garmin fēnix 6 missed a lab test by about 7 percent on average in 19 adults. Outdoor runs and your real max heart rate in the profile help most.

It’s easy to treat the number as gospel and worry when it drops a point, or to write it off as a made-up score after it jumps following one odd run. It’s an estimate with a known size of error, and it’s good at the job it’s built for, which is following your fitness over months.

We’d trust a Garmin to within about 5 points for one person and follow its trend, with your max heart rate set from a real hard effort.

What the studies found

• One watch, 19 adults. In a 2025 test, a fēnix 6 came within about 7 percent of a lab mask test on average, close to the lab value on average with no clear lean high or low. The researchers judged it acceptably accurate. At a typical 45, 7 percent is about 3 points.
• Fourteen studies pooled. A 2022 review found watches that estimate from exercise (Garmin among them) were right on average, but one person’s estimate could sit up to about 10 points either side. That works out to about 5 points either way for 2 people in 3.
• Thirteen studies, mostly Garmin. A 2025 review recommended these estimates for healthy untrained adults, recreational athletes and team-sport players. For elite endurance athletes it found too few studies to say.

Apple Watch Series 10, by comparison, came in 6.25 points low on average in its 2026 lab check (see is Apple Watch VO2 max accurate?).

How Garmin guesses

Garmin’s estimate comes from Firstbeat Analytics. It compares your heart rate with your running pace (or with power on a bike), the way you’d guess an engine’s power from how hard it revs at a known speed. Garmin’s manual says the estimate “may seem inaccurate at first,” because the watch needs a few runs to learn about you.

What throws it off

• Your max heart rate. The watch judges how hard you’re working against your max. In 3,320 Norwegians with a verified max test, the best age formula missed a person’s real max by about 11 beats for 1 in 3 people. Set yours in the profile if you know it (the heart rate zones tool shows three formulas).
• The kind of run. It needs at least 10 minutes outdoors at 70 percent of your max heart rate or more. Garmin lets you turn off VO2 max recording for trail and ultra runs.
• Your profile. Garmin asks you to fill in the user profile for the most accurate estimate.

The labels are a different chart

Garmin’s Superior to Poor colors come from The Cooper Institute’s data, which run well above the US FRIEND chart this site uses. A man in his 40s at 41 is “Fair” on Garmin (its 40th to 60th percentile) and at about the 70th percentile on FRIEND. The calculator below ranks your number on FRIEND.

Garmin’s other wrist estimate, HRV, has its own page at hrv.guide on Garmin. To find the number on your watch, see how do I see my VO2 max on Garmin?

Where does your number come from?

Apple Watch± 6.1Garmin± 5Fitbit± 8Oura or WHOOP± 812-minute run± 71.5-mile run± 71-mile walk± 4.4Beep test± 4.4Resting heart rate± 4.7Lab testmeasured

About you, and your number

Ageyrs

Sex

WomanMan

What your Garmin saysml/kg/min

33to43ml/kg/min, likely range. Most likely 38.0.

38

10th22.125th28.250th35.375th43.090th50.8

LowLowBelow averageBelowAbove averageAboveHighHighTop 10%

You have the engine of a 39-year-old

38 is about the 60th percentile for men in their 40s. Group: above average

How far to trust it. Watches that estimate from your runs came out right on average across 14 studies, give or take about 5 for one person. Outdoor runs and a set max heart rate help most. The INTERLIVE network, a review of 14 studies, 2022

When is a change real? Compare a source only with itself. A change smaller than about 2 to 4 points can be noise: a review of 14 studies put a meaningful change at 1.75 to 3.5 ml/kg/min.

Where you standRaise it with the 4x4Get your true VO2 max