What VO2 max is, and how this page estimates it
VO2 max is a measure of aerobic capacity: roughly how much oxygen your body can use during hard work, expressed in milliliters per kilogram per minute. A true measurement uses a graded exercise test with a mask. This page offers three field estimates so you can get a planning number from a run or from heart-rate data you already have.
The Cooper 12-minute test (Cooper, 1968) uses distance covered in 12 minutes: VO2 max = (meters − 504.9) / 44.73. It assumes you ran (or ran and walked) as far as you could in that window on a measured track or a reliable GPS route. The 1.5-mile option uses the ACSM running cost equation on level ground: oxygen cost rises with speed, which is why a faster 1.5-mile time produces a higher estimate. Written out, that is 3.5 + 0.2 × speed in meters per minute, or about 3.5 + 483 / time in minutes for a 1.5-mile run.
The heart-rate method follows Uth, Sørensen, Overgaard, and Pedersen (2004): VO2 max ≈ 15.3 × (HRmax / HRrest). If you do not have a measured maximum heart rate, the page uses the Tanaka equation (208 − 0.7 × age) as a stand-in. Resting heart rate should be taken when you are truly at rest, not after coffee or a walk up the stairs. This method is convenient and also noisy: medications, stress, and a bad max-HR estimate all move the result.
Field tests can be off by a meaningful margin compared with a laboratory test, especially if the route was not level, the effort was not all-out, or the distance was mis-measured. Use the same method over time if you want to see a trend. Do not treat a single number as a medical diagnosis or as a reason to ignore symptoms during exercise.
If you want training zones from heart rate, open the heart rate zone calculator. To turn a time into a pace, use the running pace calculator.
Frequently asked questions
What is a “good” VO2 max?
It depends on age, sex, and training history, and published charts disagree at the edges. This page reports the estimated number and leaves classification to sources you trust, or to a clinician when the question is medical. Comparing your number only with your own previous tests, taken the same way, is usually more useful than chasing a chart.
Should I do the Cooper test or the 1.5-mile run?
Pick the one you can measure cleanly. A track 1.5-mile time is a common military-style test. The Cooper test is handy if you would rather run for a fixed 12 minutes and measure distance. Do not mix the two protocols in your head: a 12-minute distance and a 1.5-mile time are different inputs.
Why is the heart-rate estimate so different from my watch?
Watches use their own models, often from a mix of heart rate, pace, and personal history. The Uth formula is a simple ratio of max to rest. Neither is a lab test. Large gaps are common and are not automatically a bug in the calculator.
Can I use this if I walk part of the test?
The Cooper formula still accepts the distance you covered, including walk breaks, but the estimate assumes an all-out aerobic effort. Walking a large share of the 12 minutes will usually produce a lower — and less comparable — number. The 1.5-mile ACSM option assumes running, not walking.
Is it safe to run an all-out test?
An all-out 12-minute or 1.5-mile effort is hard. Skip it if you have been told to limit intense exercise, if you feel unwell, or if you are new to running. A heart-rate estimate from easy resting data is the lower-stress option on this page, with its own accuracy limits.