What Is a VO2 Max Race Time Calculator?
This calculator estimates VDOT — Jack Daniels' running-specific measure of VO2 max — directly from a recent race performance, using the published formulas from Daniels' Running Formula. It also uses the well-known Riegel formula to predict roughly equivalent times at other common race distances, so you can see how a 5K result compares to a 10K, half marathon or marathon effort at the same fitness level.
Runners and coaches use VDOT for two main things: tracking fitness changes over time from race results alone, and setting training paces (easy, threshold, interval) that match current fitness rather than guesswork.
How to Read Your Results
Estimated VDOT (VO2 max)
Your race-derived VO2 max estimate. Recreational runners are commonly in the 30s–40s, competitive club runners in the 50s–60s, and elite runners in the 70s and above.
Race Pace
Your average pace for the entered race, shown in minutes per kilometer.
Predicted 10K / Half Marathon / Marathon
Roughly equivalent times at other distances if your fitness stayed constant, based on the Riegel exponential fatigue model. These become less reliable the further the target distance is from your input race, especially for the marathon.
Real-World Example
A runner finishes a 5,000m race in 25:00.
| Metric | Result |
|---|---|
| Race pace | ≈5:00 /km |
| Estimated VDOT | ≈38.3 |
| Predicted 10K | ≈52:07 |
| Predicted half marathon | ≈1:55:00 |
That 25:00 5K corresponds to a VDOT of roughly 38, which matches published Daniels VDOT tables closely — a useful cross-check that the calculator is working as intended.
Tips for Using VDOT
- Recalculate after every serious race to track whether your aerobic fitness is trending up or down.
- Use a recent race, not an old one — VDOT reflects current fitness, and it changes with training.
- Predicted times work best for nearby distances — a 5K-to-10K prediction is more reliable than a 5K-to-marathon prediction, since the marathon also depends heavily on fueling, pacing discipline and endurance training that a short race doesn't test.
- Pair VDOT with a training pace chart to set accurate easy, tempo and interval paces rather than guessing.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team