What is fitness age?
Fitness age is the age at which your VO2 max would be exactly average. A 45-year-old man at 42 has the engine of a typical 32-year-old. We place your number on the US treadmill chart built from 16,278 lab tests.
There are several fitness ages going around, and they rarely agree. A popular calculator from the Norwegian University of Science and Technology estimates your fitness from a questionnaire (your age, waist or BMI, how active you are and your resting heart rate). Apple’s new Health Age, announced in September 2026, can factor in VO2 max along with resting heart rate, sleep and HRV. The same person can get different ages from each.
We think fitness age is the clearest way to see what a VO2 max number means, and the best one to share. The fitness age on this site starts from a measured or estimated number (from a lab, a field test or a watch) and puts it on the US chart, so it changes when your fitness does.
How it’s worked out
The US FRIEND chart gives the middle VO2 max for each decade, men and women separately. We draw a straight line through those middles at ages 25, 35, 45 and so on up to 85, then find the age where your number sits on the line.
| Number | A man’s fitness age | A woman’s fitness age |
|---|---|---|
| 50 | 25 or younger | 25 or younger |
| 42 | 32 | 25 or younger |
| 38 | 39 | 25 or younger |
| 35 | 45 | 27 |
| 30 | 54 | 33 |
| 25 | 64 | 48 |
| 20 | 77 | 64 |
Above the middle for people in their 20s (46.5 for men, 36.6 for women) we say “25 or younger”, since the chart doesn’t go younger. Below the middle for people in their 80s (17.6 and 15.4) we say “85 or older”.
Your fitness age equals your real age when you’re exactly average. If it’s lower, you’re above the middle for your age.
A number you can move
Fitness age is the easiest way to see a training result. The five Dallas men, tested again at 50, had a VO2 max of 31, a fitness age of about 52. Six months of endurance training brought them to 36, a fitness age of about 43, nine years younger in half a year.
Canadian physiologist Roy Shephard wrote that regular aerobic exercise can take 10 or more years off your biological age, and keep you living on your own for about as long.
What it leaves out
It’s built on one number, so it says nothing about strength, balance or blood pressure. It’s only as good as the number you put in, and an Apple Watch came in about 6 points low in lab checks, which would add years. A bike test is ranked on the bike chart, since bike numbers run lower.
Find yours in the tool below, then see what’s a good VO2 max for my age? or the quiz for a plan to bring it down.
What your result means, and what to do next
- Low or below average. Most of the health gap sits in the first step up, so this is where training pays the most.
- Above average or high. Hold it as the years pass. Holding steady after 40 already counts as climbing.
- The next group up is a target for one training block, but people respond very differently, from almost nothing to a lot.
- Make sure the number is real. A watch can be several points off. Get your true VO2 max
- Start the two layers. Cardio most days at a pace where you can still talk, and one or two hard sessions a week. How to raise it
- Retest the same way in 8 to 12 weeks. Same test, same route or same watch. Believe a change of more than 2 to 4 points.
5 sources
- Kaminsky LA and others, Updated reference standards for cardiorespiratory fitness measured with cardiopulmonary exercise testing (FRIEND), Mayo Clinic Proceedings, 2022mayoclinicproceedings.org
- Norwegian University of Science and Technology, CERG fitness calculator, checked 2026-11-14ntnu.edu
- Apple Newsroom, Apple advances health and fitness capabilities using Apple Intelligence, September 2026apple.com
- McGuire DK and others, A 30-year follow-up of the Dallas Bedrest and Training Study: II. Effect of age on cardiovascular adaptation to exercise training, Circulation, 2001europepmc.org
- Shephard RJ, Maximal oxygen intake and independence in old age, British Journal of Sports Medicine, 2009europepmc.org
