VO₂max percentile calculator by age and sex

How does the calculator place your VO₂max?

VO₂max is your aerobic capacity. It is the most oxygen your body can use when you go all-out. The unit is mL/kg/min. It counts the milliliters of oxygen your body uses in a minute for every kilogram you weigh.

The calculator compares your number with lab tests from the FRIEND registry. FRIEND is short for the Fitness Registry and the Importance of Exercise National Database. Its 2022 update printed VO₂max percentiles for men and women in each decade of age from 20 to 89^[1].

A percentile is a place in a group of 100. At the 68th percentile, 68 of every 100 people in the group scored lower than you.

You can type a number from a lab test or from your watch. Apple Watch shows its estimate as Cardio Fitness in the Health app, and Cardio Fitness on Apple Watch shows where to find it.

How the math works

1. Your row. The calculator picks the table for your sex and the row for your decade of age. A 34-year-old woman reads the row for women aged 30 to 39.
2. The nine cut points. Each row prints nine VO₂max values. There is one at every 10th percentile from the 10th to the 90th^[1].
3. The straight line. Your number lands between two of those cut points. The calculator draws a straight line between them and reads your place off that line.
4. The two ends. A number at or above the row's 90th percentile reads as more than 90 out of 100. A number at or below the 10th reads as fewer than 10 out of 100. The table prints nothing past those two points, so the calculator does not guess there.
5. The result. The calculator says how many of 100 people your age and sex had a lower VO₂max in the registry. Your age here means your decade.

Take the 34-year-old woman with a VO₂max of 33. Her row puts the 60th percentile at 31.0 and the 70th at 33.6^[1]. Her 33 is 2.0 points above 31.0. The whole gap between the two cut points is 2.6 points. So 33 is about 77% of the way from the 60th to the 70th. That puts her at about the 68th percentile.

The result is an estimate. The registry printed only nine points in each row. The straight line between two of them is a best guess for the people in between.

The calculator gives no place for ages under 20 or over 89, because the registry's rows run from 20 to 89. It also needs your sex. The registry worked out separate percentiles for men and women, so the calculator needs one of the two tables to find your row^[1].

Where do a few example numbers land?

The table below runs six example readers through the calculator. Each one uses the FRIEND treadmill row for that person's age and sex^[1].

The man aged 28 with a VO₂max of 41 lands below the middle of his row. Out of 100 men in their 20s tested in the registry, about 33 had a lower VO₂max. About 67 had a higher one.

The man aged 35 with a VO₂max of 24 reads fewer than 10 out of 100. His row puts the 10th percentile at 24.9, and his 24 is under it. The table prints no point below the 10th, so the calculator gives no closer number.

Who was tested in the FRIEND registry?

The registry's tests came from 34 labs across the United States and ran from 1968 to 2021^[1]. The 2022 update counted 22,379 of them, all from healthy adults aged 20 to 89. Each test measured the oxygen a person used as the work got harder until they could not go on. A test made it into the tables only when the breathing data showed an all-out effort^[1].

Of those tests, 16,278 were on a treadmill, and the calculator reads only those. The registry's 50th percentile came out higher on a treadmill than on a bike^[1]. A number from running or walking matches the treadmill table best.

The authors wrote that the 2022 tables reflect the United States population better than the registry's first tables from 2015^[1]. The guide to VO₂max by age prints the full table for both sexes.

How far can a watch estimate move your place?

Apple Watch estimates VO₂max during Outdoor Walk, Outdoor Run and Hiking workouts^[4]. The watch reads how your heart rate responds to the work and estimates VO₂max from that^[3]. The estimate can land several points from a lab test.

A 2026 study tested the Apple Watch Series 10 against a lab treadmill test in 35 adults^[2]. They averaged 23 years old, and 25 of the 35 placed at the 80th percentile or higher in the lab. The watch read 6.25 mL/kg/min below the lab on average. Its miss averaged 6.8 points in either direction. Only 5 of the 35 landed in the same FRIEND percentile band on the watch as in the lab^[2].

Here is what a miss of about 7 points does to one reader. The woman aged 34 with a VO₂max of 33 is at about the 68th percentile. A reading of 40 would put her at about the 86th. A reading of 26 would put her at about the 38th^[1].

The middle of each row is crowded. Each step of 10 percentiles from the 40th to the 60th spans 3.7 points or less in every row^[1]. The steps get narrower with age. Women in their 60s reach the 40th, 50th and 60th percentiles at 18.3, 19.6 and 20.9^[1].

So read a watch number on this calculator as a rough place. A trend across months of the same kind of outdoor workout tells you more than one reading. Apple Watch VO₂max accuracy covers each study and the things that throw the estimate off.

How does training move your place?

A 2015 review pooled 28 studies with 723 adults who averaged 25 years old^[5]. They started at a VO₂max of 40.8 on average. Steady endurance training raised VO₂max by 4.9 mL/kg/min more than no training did. Interval training raised it by 5.5 more^[5].

Five points is a big move on this chart. The man aged 28 with a VO₂max of 41 is at about the 33rd percentile. The 50th percentile in his row is 46.5, which is 5.5 points higher^[1]. That gap is the same size as the average gain from interval training in the review.

Older people gain too. A small study had eight men who averaged 68 years old cycle for 45 minutes three times a week^[8]. Their VO₂max rose 31% in 12 weeks.

One 8-week study split 40 moderately trained men into four groups that trained three days a week with the same total work^[6]. The group that ran four 4-minute intervals at 90 to 95% of max heart rate went from 55.5 to 60.4 mL/kg/min. Running the same work at a steady 70% or 85% of max raised VO₂max less^[6]. The row for men in their 20s puts 55.5 at about the 82nd percentile and 60.4 past the 90th^[1].

The study's range of 90 to 95% of max crosses the 92% line where Diastra's VO₂max band starts. Type your age below to see each band as a heart rate. Easy on the card is the Zone 2 most runners know.

Give a block of training about 8 weeks before you check your place again. A 2019 study had 39 adults who had been doing little exercise train three days a week^[7]. One group's VO₂max went from 24.3 at the start to 24.7 at week 4 and 25.9 at week 8. The rise was clear at week 8 and too small to be sure of at week 4^[7].

The guide on how to improve VO₂max covers how hard, how often and how long to train.

What does Diastra do with this?

Diastra reads every workout your Apple Watch saved in Apple Health. It finds your max heart rate in those workouts and draws your Easy, Threshold and VO₂max bands from that max. The watch taps your wrist when you drift out of your band, and only the minutes that held are credited. Over the weeks Diastra shows whether your training is working. Getting fitter. Holding steady. Slipping.