Last updated: 2026-06-22

Estimated VO2 Max (No Exercise Test)

VO2 max is the maximal rate at which the body can take in, transport, and use oxygen during intense effort, expressed in millilitres of oxygen per kilogram of body weight per minute. It is the standard measure of cardiorespiratory fitness. Measuring it directly requires a graded exercise test with gas analysis, but it can also be estimated from everyday characteristics. This calculator uses the non-exercise model published by Jackson and colleagues in 1990, which predicts VO2 max from sex, age, body mass index, and a self-reported physical-activity rating, with no exercise test required.

The model

The estimate comes from a linear regression fitted to a large sample of adults:

Here $\mathrm{PA}$ is the physical-activity rating, age is in years, $\mathrm{BMI}$ is body mass index in $\mathrm{kg/m^2}$, and $S$ is a sex term equal to one for men and zero for women. The result is in mL/kg/min. Body mass index is computed from height and weight before it enters the equation. Each coefficient reflects the average contribution of that variable: more reported activity and male sex raise the estimate, while greater age and a higher body mass index lower it.

The physical-activity rating scale

The activity rating is a single self-reported number from 0 to 7, sometimes called the NASA or Jackson physical-activity scale. It asks which description best matches typical activity over the past month. Ranks 0 to 3 cover sedentary to light routines; ranks 4 to 7 describe regular vigorous exercise, graded by weekly running distance or its equivalent in minutes.

Choosing the rank that honestly reflects a typical month, rather than a best week, gives the most reliable estimate.

Worked example

Consider a man aged 35 with a height of 1.78 m5 ft 10 in and a weight of 75 kg165 lb who reports a physical-activity rating of 4. Body mass index comes first, then the regression:

An estimate near 44 mL/kg/min is a typical value for a moderately active man of that age.

Interpreting the result

VO2 max is read against age- and sex-specific norms rather than a single universal cut-off. Reference tables such as those published by the Cooper Institute and used in ACSM guidance report fitness percentiles separately for each age band and for men and women, because expected values fall with age and differ between the sexes. A figure that is average for one group may be high or low for another, so the estimate is most meaningful when compared with the norms for the matching age and sex. For one person, the direction of change across several estimates is usually more informative than a single reading.

Accuracy and limits

The non-exercise model trades precision for convenience. In the original study it predicted measured VO2 max with a standard error of roughly 5 mL/kg/min, so an individual estimate can be off by several units. It is most reliable near the centre of the population it was built on and weaker at the extremes of fitness, and it cannot capture training history, genetics, or health conditions beyond what the four inputs imply.

For a measured estimate based on a submaximal effort, the VO2 Max Calculator calculator uses a field or step test instead of a self-report, which generally improves accuracy at the cost of performing the test. To apply a VO2 max or maximum heart rate to training intensity, see Heart Rate Zones Calculator. Any estimate here is a screening figure, and decisions about training or health should rest on professional advice rather than a single number.