Fitness age and VO₂ max, explained
Your fitness age is the age at which your VO₂ max would be average. VO₂ max is the most oxygen your body can use during hard exercise, measured in mL per kg of body weight per minute. This calculator estimates it without a treadmill, from your age, sex, BMI and how active you are (Jackson et al., 1990). If your VO₂ max is above average for your age, your fitness age is younger than your real age.
Why it matters: in 122,007 adults who did a treadmill test, the least fit group had about 5 times the risk of death of the fittest group (Mandsager et al., JAMA Network Open 2018).
How to calculate your fitness age
The calculator works in two steps:
- Estimate VO₂ max with the Jackson non-exercise model: 56.363 + 1.921 × activity rating − 0.381 × age − 0.754 × BMI + 10.987 (men only). The activity rating is the 0–7 scale in the form, from “avoid exertion” (0) to “run 10+ miles or 3+ hours of hard exercise a week” (7).
- Find your fitness age: the age at which the average VO₂ max in our reference line equals yours. The reference line is 57.8 − 0.445 × age for men and 47.4 − 0.37 × age for women.
Worked example. A 40-year-old man, 175 cm and 78 kg (BMI 25.5), who does an hour or more of light or some moderate activity a week (rating 3), gets an estimated VO₂ max of 38.7 mL/kg/min. The average on our reference line is 38.7 at age 43, so his fitness age is 43.
The idea of a fitness age was popularised by Norway’s HUNT Study at NTNU, which also offers its own fitness calculator. A non-exercise estimate is useful for tracking, but a lab test, or a field test such as a timed run, is more precise for any one person.
What is a good VO₂ max for my age?
This table shows the reference averages the calculator uses, and the level at which it rates your fitness as excellent (15% or more above average for your age and sex).
| Age | Men: average | Men: excellent | Women: average | Women: excellent |
|---|---|---|---|---|
| 20 | 48.9 | 56.2+ | 40.0 | 46.0+ |
| 30 | 44.4 | 51.1+ | 36.3 | 41.7+ |
| 40 | 40.0 | 46.0+ | 32.6 | 37.5+ |
| 50 | 35.5 | 40.9+ | 28.9 | 33.2+ |
| 60 | 31.1 | 35.8+ | 25.2 | 29.0+ |
| 70 | 26.6 | 30.6+ | 21.5 | 24.7+ |
| 80 | 22.2 | 25.5+ | 17.8 | 20.5+ |
The calculator rates your level by comparing your VO₂ max with the average for your age and sex: excellent at 115% or more, good at 102–115%, average at 90–102%, below average at 78–90% and low below 78%.
Fitness falls with age for everyone, but it falls more slowly in people who keep training. Each 1-MET (3.5 mL/kg/min) higher fitness level was linked to about 13% lower risk of death from any cause in a meta-analysis of 33 studies (Kodama et al., JAMA 2009).
How to improve your fitness age
- Move up one activity level. Each step on the 0–7 activity scale adds about 1.9 mL/kg/min to your estimate, which takes about 4 years off a man’s fitness age and about 5 years off a woman’s.
- Include some harder sessions. Brisk walking builds a base. Intervals, such as 4 × 4 minutes at a hard but steady effort with easy recovery in between, raise VO₂ max further.
- Meet the basic guideline. At least 150 minutes of moderate or 75 minutes of vigorous activity a week, plus muscle-strengthening on 2 days (CDC).
- Bring your BMI toward the healthy range. VO₂ max is measured per kg of body weight, so each BMI point lower adds about 0.75 to your estimate.
See how activity changes your overall estimate in the add-years simulator and your biological age.
Fitness age FAQ
What is fitness age?
Fitness age is the age at which your cardio fitness (VO₂ max) would be average. If you are 50 with the VO₂ max of an average 40-year-old, your fitness age is 40.
How do I calculate my fitness age?
Enter your age, sex, height, weight and activity level above. The calculator estimates your VO₂ max with the Jackson non-exercise model, then finds the age at which that VO₂ max is average.
What is a good VO₂ max for my age?
On this calculator’s reference line, the average for a 40-year-old man is 40.0 mL/kg/min and for a 40-year-old woman 32.6. A value 15% or more above the average for your age and sex counts as excellent.
How accurate is a VO₂ max estimate without a test?
It is a reasonable estimate for groups of people, but individual results can be off by several mL/kg/min. A lab test with breathing analysis is the most accurate. Watch estimates also vary between brands.
Can I lower my fitness age?
Yes. VO₂ max responds to training at any age. More regular activity, some harder sessions and a lower BMI all raise your estimate and lower your fitness age.
Why does cardio fitness matter for lifespan?
Higher cardio fitness is one of the strongest predictors of a longer life in large studies. In a study of 122,007 adults, the least fit had about 5 times the risk of death of the fittest.
Last reviewed: · Sources · Educational estimate, not medical advice.
Sources
- Jackson AS, Blair SN, Mahar MT, et al. Prediction of functional aerobic capacity without exercise testing. Med Sci Sports Exerc, 1990;22:863–870.
- Mandsager K et al. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open, 2018.
- Kodama S et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA, 2009.
- NTNU Cardiac Exercise Research Group. Fitness calculator (HUNT Study).
- CDC. Adult Activity: An Overview.