How it works
pace(zone) from VDOT at the zone’s % of VO₂ max (Daniels)
Each training zone has an intensity expressed as a fraction of your VO₂ max. We take that fraction of your VDOT as a target oxygen cost and invert Daniels’ oxygen-cost curve to find the running velocity — and therefore the pace — that matches it. The intensity each zone targets, and the adaptation it drives, are: | Zone | % VO₂ max | What it trains | | --- | --- | --- | | Easy / long | 59–74% | Aerobic base, capillaries, fat metabolism — most weekly volume | | Marathon | ~82% | Marathon-specific endurance and running economy | | Threshold (tempo) | ~88% | Raises the speed you can hold before fatigue accelerates | | Interval (VO₂ max) | 100% | Maximal aerobic power; ~3–5-min reps near vVO₂ max | The percentages above are the exact intensity fractions this tool applies to your VDOT (easy is a range; the others are single targets); they sit at the top end of Daniels’ published zones. Repetition pace — short, fast, anaerobic reps — is not derived from VO₂, so it is best taken from your mile race pace instead. Worked example. A VDOT of 50 (a runner who races 5K in about 19:57) yields an easy range of about **7:52–9:26 /mi** (4:54–5:52 /km), marathon pace **7:15 /mi** (4:30 /km), threshold **6:51 /mi** (4:15 /km), and interval **6:10 /mi** (3:50 /km) — the same numbers this calculator returns for VDOT 50. Everything is computed in metres and seconds and converted at the edge, so the per-mile and per-kilometre paces always agree.
Sources
- Daniels’ training paces Jack Daniels, “Daniels’ Running Formula” (Human Kinetics) — Easy, Marathon, Threshold and Interval paces by VDOT.
- Daniels & Gilbert VDOT Jack Daniels & Jimmy Gilbert, “Oxygen Power: Performance Tables for Distance Runners” (1979) — the VO₂–velocity relationship behind VDOT and the training paces.
- Easy-running intensity Daniels, Daniels Running Formula, 3rd ed. (2013), Human Kinetics — easy/long-run effort at roughly 59–74% of VO₂ max, the basis for the easy pace range; threshold ~88% and interval 100% of VO₂ max.
FAQ
What are Daniels training paces?
A set of paces — easy, marathon, threshold and interval — each tied to a specific training intensity. Running each workout at its prescribed pace targets a particular adaptation, from aerobic base in easy runs to VO₂ max in intervals, without overcooking the easy days.
Which race should I enter?
A recent, hard race over roughly 1.5 km to the half marathon gives the most reliable VDOT and therefore the most accurate paces. A 5K or 10K works well. If you race rarely, use your best recent effort and re-check after your next race.
How fast should my easy runs be?
Easy is a range, not a single number — roughly 59–74% of VO₂ max. The point is comfort: you should be able to hold a conversation. Most runners err by going too fast on easy days, which blunts recovery and the quality of hard sessions.
What is threshold pace?
Threshold (or tempo) pace is a comfortably hard effort you could sustain for about an hour in a race — near 88% of VO₂ max. Tempo runs and cruise intervals at this pace raise the speed you can hold before fatigue accelerates.
How fast should a tempo run be?
A tempo run is held at threshold pace — about 88% of VO₂ max, the effort you could race for roughly an hour, or "comfortably hard." For a VDOT of 50 that works out to about 6:51 /mi (4:15 /km); enter your own race above to get your number. Keep it controlled: a true tempo should feel sustainable, not like a race.
What pace is threshold for my VDOT?
Threshold pace falls out of your VDOT at 88% of VO₂ max. A VDOT of 50 gives 6:51 /mi (4:15 /km); a fitter VDOT yields a faster threshold. Compute your VDOT from a race with the VDOT calculator, then read your threshold here.
How fast should easy runs be?
Easy runs sit at 59–74% of VO₂ max — a range, not one number, run at a conversational effort. For a VDOT of 50 that is roughly 7:52–9:26 /mi (4:54–5:52 /km). To cross-check by effort, train easy days inside your aerobic heart rate zones.
Why is there no repetition (R) pace here?
Repetition work is short, fast and anaerobic, so it is not well described by the VO₂-based model used for the other zones. Daniels sets R pace close to your mile race pace instead — use a race-time predictor or your mile time for those reps.
How often should I update my paces?
Whenever your fitness changes meaningfully — typically after a new race result. As your VDOT rises, your training paces should get a little faster. Re-enter your latest race here to keep them current.
Training paces are estimates from the Daniels model and your race result, not personalised coaching. Adjust for heat, terrain, fatigue and how you feel. General information for training, not medical advice.