What VO2 max is
VO2 max is the most oxygen your body can take in and use per minute, scaled to your body weight, in millilitres per kilogram per minute. It sets the ceiling on sustained endurance performance. Measuring it properly means a mask, a treadmill and a laboratory; everything on this page is an estimate from something easier to do.
The Cooper 12-minute run
Kenneth Cooper published this field test in 1968 after comparing how far military personnel could run in twelve minutes with their treadmill-measured oxygen uptake. Run as far as you can in exactly twelve minutes on a flat, measured course, then:
VO2 max = (metres covered − 504.9) ÷ 44.73
Two things decide whether the number means anything. The effort has to be genuinely maximal — the test is unpleasant when done correctly — and the pacing has to be even. Starting too fast is the usual failure: blowing up at eight minutes can cost several hundred metres, which is several points of VO2 max.
Estimating it from heart rate
If an all-out twelve minutes is not available to you, Uth and colleagues (2004) found that the ratio of maximum to resting heart rate tracks VO2 max reasonably well:
VO2 max ≈ PF × (HRmax ÷ HRrest)
The proportionality factor PF is 15.3 for men, from that 2004 study of 46 well-trained men, and 14.5 for women, from Uth’s 2005 follow-up on 27 trained women, which found the factor differs by sex because women have a lower mass-specific resting oxygen uptake. Using 15.3 for a woman overestimates her result by about 5%, so the calculator above picks the factor from the sex you select.
Both factors were fitted in trained people, so treat the result as a population estimate rather than a personal measurement. It also needs a real maximum heart rate from a hard effort, not the 220-minus-age rule of thumb, which is a population average with a standard deviation of around ten beats and will quietly make this figure meaningless.
VO2 max by age and sex
These are measured values, not estimates: percentiles from treadmill cardiopulmonary exercise tests in the FRIEND registry (Kaminsky et al., 2015), the first such reference data for the United States. Fitness falls about 10% per decade across this sample.
Men (mL/kg/min)
| Age | 5th | 10th | 25th | 50th | 75th | 90th | 95th |
|---|---|---|---|---|---|---|---|
| 20–29 | 29.0 | 32.1 | 40.1 | 48.0 | 55.2 | 61.8 | 66.3 |
| 30–39 | 27.2 | 30.2 | 35.9 | 42.4 | 49.2 | 56.5 | 59.8 |
| 40–49 | 24.2 | 26.8 | 31.9 | 37.8 | 45.0 | 52.1 | 55.6 |
| 50–59 | 20.9 | 22.8 | 27.1 | 32.6 | 39.7 | 45.6 | 50.7 |
| 60–69 | 17.4 | 19.8 | 23.7 | 28.2 | 34.5 | 40.3 | 43.0 |
| 70–79 | 16.3 | 17.1 | 20.4 | 24.4 | 30.4 | 36.6 | 39.7 |
Women (mL/kg/min)
| Age | 5th | 10th | 25th | 50th | 75th | 90th | 95th |
|---|---|---|---|---|---|---|---|
| 20–29 | 21.7 | 23.9 | 30.5 | 37.6 | 44.7 | 51.3 | 56.0 |
| 30–39 | 19.0 | 20.9 | 25.3 | 30.2 | 36.1 | 41.4 | 45.8 |
| 40–49 | 17.0 | 18.8 | 22.1 | 26.7 | 32.4 | 38.4 | 41.7 |
| 50–59 | 16.0 | 17.3 | 19.9 | 23.4 | 27.6 | 32.0 | 35.9 |
| 60–69 | 13.4 | 14.6 | 17.2 | 20.0 | 23.8 | 27.0 | 29.4 |
| 70–79 | 13.1 | 13.6 | 15.6 | 18.3 | 20.8 | 23.1 | 24.1 |
Compare like with like: your field estimate is not the same quantity as a laboratory measurement, and the two can differ by several points in either direction. The table is most useful for the broad answer — roughly where you sit — rather than for deciding you are at the 62nd percentile rather than the 58th.
What a given VO2 max means
There is no single good number, and no ideal range. A VO2 max only means something once you say who it belongs to, because the same figure moves across the whole distribution as age and sex change. Take 37.6, read off the tables above:
- A man of 25: between the 10th and 25th percentile for his age group, whose median is 48.0. Well below average.
- A man of 65: between the 75th and 90th percentile, against a median of 28.2. Comfortably above average.
- A woman of 25: 37.6 is the median for women aged 20–29 — exactly average.
One number, three different answers. This is why “is 45 good?” has no useful reply on its own, and why charts giving a single good-to-excellent scale for everyone are misleading.
At the top end the distribution runs out quickly. The 95th percentile for men aged 30–39 is 59.8, so a measured 80 at that age is not merely excellent — it is off the scale of a general population sample, the territory of trained endurance athletes. A watch reporting a number that high is far more likely to be wrong than remarkable.
The honest way to read your own figure: find your age group and sex in the tables above, compare against the median in the 50th column, and treat anything inside roughly the 25th to 75th as ordinary for who you are.
Why your watch disagrees
Sports watches estimate VO2 max from the relationship between running speed and heart rate, each using its own undisclosed model. They are consistent with themselves, which makes the trend over months genuinely useful, and inconsistent with everything else, which makes the absolute number a poor thing to quote. If your watch says 48 and the Cooper test says 44, neither is wrong exactly — they are different estimates of a thing neither has measured.
What to do with the number
Less than people hope. VO2 max sets a ceiling, but race performance depends at least as much on the fraction of that ceiling you can hold, and on running economy. Two runners with the same VO2 max can finish a marathon a long way apart. If you want a number that predicts race day, a recent race result is a better one — see the marathon pace calculator for turning a goal into splits, and the grade-adjusted pace calculator for comparing efforts across terrain.
As a training signal, the useful question is not “what is my VO2 max” but “is it moving”. Retest the same way, on the same course, a few months apart.
Frequently asked questions
What is a good VO2 max for my age?
Against measured reference values from the FRIEND registry, the median for men aged 20–29 is 48.0 mL/kg/min and for women 37.6. By 50–59 those medians fall to 32.6 and 23.4. The table on this page gives every decade and percentile, so “good” is whatever beats the median for your own age and sex.
How accurate is the Cooper test?
It is an estimate from a field test, not a measurement. Cooper's 1968 equation was fitted against treadmill testing, and it assumes you ran a genuine maximal effort with even pacing on a flat, measured course. Pacing badly is the biggest source of error — going out too fast can cost you several hundred metres and several points of VO2 max.
Can I estimate VO2 max without running?
The heart rate ratio method does it from numbers you can measure at rest and at maximum: VO2 max ≈ PF × (HRmax ÷ HRrest). The proportionality factor is 15.3 for men (Uth et al., 2004) and 14.5 for women (Uth, 2005), so using one figure for everyone overestimates a woman’s result by about 5%. Treat it as a rough population estimate — both factors were fitted in trained people — and remember it still needs a real maximum heart rate rather than the 220-minus-age guess.
Why do watches give a different number?
Sports watches estimate VO2 max from the relationship between your running speed and heart rate, using each manufacturer's own model. They are consistent with themselves, which makes them useful for tracking change over time, but they are not measurements and rarely agree with each other or with a field test.
How much can VO2 max improve with training?
Untrained people typically improve substantially in the first few months of consistent endurance training; trained athletes change far less, because they are closer to their ceiling. VO2 max also declines with age — about 10% per decade in the FRIEND data — though training slows that considerably.
Sources
The formula on this page comes from the published work below. We check the numbers against the worked examples in these sources with automated tests, and re-read the page against them when we review it.
- Cooper KH. A means of assessing maximal oxygen intake: correlation between field and treadmill testing. JAMA. 1968;203(3):201–204. pubmed.ncbi.nlm.nih.gov/5694044/
- Uth N, Sørensen H, Overgaard K, Pedersen PK. Estimation of VO2max from the ratio between HRmax and HRrest — the Heart Rate Ratio Method. Eur J Appl Physiol. 2004;91(1):111–115. pubmed.ncbi.nlm.nih.gov/14624296/
- Uth N. Gender difference in the proportionality factor between the mass specific VO2max and the ratio between HR(max) and HR(rest). Int J Sports Med. 2005;26(9):763–767. pubmed.ncbi.nlm.nih.gov/16237622/
- Kaminsky LA, Arena R, Myers J. Reference standards for cardiorespiratory fitness measured with cardiopulmonary exercise testing: data from the Fitness Registry and the Importance of Exercise National Database (FRIEND). Mayo Clin Proc. 2015;90(11):1515–1523. pubmed.ncbi.nlm.nih.gov/26455884/
General fitness information, not medical advice. Results are estimates; check with a doctor or qualified coach before major changes to diet or training. Formula and copy last reviewed 31 October 2026.