Tool · Physiology
VO₂max calculator for runners
Estimate your maximal oxygen uptake from a recent race, the 12-minute Cooper test or your maximal aerobic speed. You get a single figure, Jack Daniels’ VDOT index, with your field MAS and your pace at MAS: the same calculations as in RunMorph plans.
Estimate from your race time (Jack Daniels’ VDOT model). The VO₂max shown is Jack Daniels’ VDOT index: the oxygen your performance demands, running economy included, on the same scale as in RunMorph. The rule of thumb “VO₂max ≈ 3.5 × MAS” only gives a ballpark figure. These values remain estimates and are no substitute for a lab stress test.
How to estimate your VO₂max
VO₂max is the maximum amount of oxygen your body can use during exercise, expressed in ml/kg/min. It’s one of the markers of aerobic potential. Only a lab can measure it precisely (mask and gas analysis), but three field methods give a solid estimate.
1. From a race time (VDOT method, the most reliable)
Start from a recent performance over a known distance. Jack Daniels’ equations work out the oxygen that performance demands, relative to the share of your VO₂max you can sustain for its duration: that’s the VDOT, the VO₂max shown by the calculator. Your field MAS follows from it. Example: a 10K in 50:00 gives a VDOT of about 40 ml/kg/min and a MAS of about 8.6 mph (13.8 km/h).
2. The Cooper test (12 minutes)
Run all-out for 12 minutes and measure the distance covered. The calculator treats the test as a 12-minute performance, with the same model as race times. Example: 1.74 miles (2,800 m) in 12 minutes gives a VO₂max (VDOT) of about 44 ml/kg/min and a MAS of about 9.3 mph (14.9 km/h). Cooper’s original 1968 formula, built on military personnel, often gives a higher figure.
3. From your MAS
If you already know your field MAS (half-Cooper test, stage test…), the calculator works out the matching VDOT. Example: a MAS of 9.9 mph (16 km/h) matches a VO₂max (VDOT) of about 48 ml/kg/min. The rule of thumb “VO₂max ≈ 3.5 × MAS (km/h)” would give 56: a ballpark figure, too high for most runners.
One figure, within about ±10%. Without a mask and gas analysis, any VO₂max is an estimate. VDOT has the advantage of linking VO₂max, MAS and race times on one scale: the one used on your RunMorph dashboard. The pace for a given speed is pace (min/mi) = 60 ÷ speed (mph).
MAS chart: matching VO₂max
How field maximal aerobic speed translates into estimated VO₂max (Jack Daniels’ VDOT), with your running pace at MAS. A handy benchmark to link your speed on the road to your aerobic potential.
| MAS | Pace at MAS | Estimated VO₂max (VDOT) |
|---|---|---|
| 7.5 mph | 8:00 /mi | ≈ 34 ml/kg/min |
| 8 mph | 7:30 /mi | ≈ 37 ml/kg/min |
| 8.5 mph | 7:04 /mi | ≈ 40 ml/kg/min |
| 9 mph | 6:40 /mi | ≈ 43 ml/kg/min |
| 9.5 mph | 6:19 /mi | ≈ 45 ml/kg/min |
| 10 mph | 6:00 /mi | ≈ 48 ml/kg/min |
| 10.5 mph | 5:43 /mi | ≈ 51 ml/kg/min |
| 11 mph | 5:27 /mi | ≈ 54 ml/kg/min |
| 11.5 mph | 5:13 /mi | ≈ 58 ml/kg/min |
| 12 mph | 5:00 /mi | ≈ 61 ml/kg/min |
These values come from Daniels’ equations, the same as the calculator and RunMorph. They remain estimates, within about ±10%.
Frequently asked questions
What is VO₂max in running?
VO₂max is the maximum amount of oxygen your body can use per minute during intense exercise. It’s expressed in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min). The higher it is, the greater your aerobic potential. Recreational runners often sit between 40 and 55 ml/kg/min; elites go above 70.
How can I estimate my VO₂max without a lab test?
Three accessible methods: (1) from a recent race time (5K, 10K, half…), using Jack Daniels’ VDOT index, the most reliable because it reflects a real performance; (2) with the Cooper test: run all-out for 12 minutes, and this 12-minute performance goes through the same Daniels model; (3) from your field maximal aerobic speed, the speed you hold for about 6 minutes. This calculator offers all three and gives a single figure, the VDOT, within about ±10%.
What’s the difference between VO₂max and MAS?
VO₂max is an oxygen uptake (in ml/kg/min); MAS, or maximal aerobic speed, is a running speed, the one you hold for about 6 minutes all-out. MAS turns VO₂max into a real-world speed you can use straight away to set your paces. The rule of thumb “VO₂max ≈ 3.5 × MAS (km/h)” gives a ballpark figure; this calculator converts one into the other with Daniels’ equations, which factor in running economy: a MAS of 15 km/h (9.3 mph) matches a VO₂max (VDOT) of about 44 ml/kg/min.
Why talk about VDOT rather than VO₂max?
Jack Daniels’ VDOT isn’t a VO₂max measured in a lab: it’s the VO₂max “equivalent” to your performance, running economy included (the oxygen you actually spend to run at a given speed). It links VO₂max, MAS and race times directly, which makes it the best benchmark for training. It’s also the VO₂max shown in RunMorph. It’s often lower than the result of the “3.5 × MAS” rule, which gives a higher figure for most runners.
Is the Cooper test a reliable way to estimate VO₂max?
The Cooper test (12 minutes at maximal effort) gives a good estimate for a trained runner who can hold a steady, truly maximal pace for the whole duration. The calculator treats it as a 12-minute performance, with the same model as race times, so that every result speaks the same language. Its accuracy depends on how honest the effort is, the surface (ideally a flat track) and the weather. For a more stable benchmark, an estimate from a race time is still the better choice.
Turn your VO₂max into a training plan
RunMorph starts from your field maximal aerobic speed to work out your 7 pace zones and build a session-by-session plan, periodized all the way to race day.
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