How it works
pace(zone) from VDOT at the zone’s % of VO₂ max (Daniels)
Every zone is defined as a slice of your aerobic ceiling. Easy running sits at 59–74% of VO₂ max, marathon effort near 82%, threshold near 88%, and interval work at the full 100% — fractions taken from Daniels’ published system. The calculator applies each fraction to your VDOT as an oxygen budget, then traces the pace-to-oxygen relationship backwards until it finds the speed that spends exactly that budget; that speed, formatted per mile and per kilometer, is what lands in your zone table. Interval reps are meant to last roughly 3–5 minutes; shorter, faster repetition work is tied to mile race speed rather than VO₂, so Daniels handles it outside this model and the page leaves it out on purpose. For calibration: VDOT 50 — about a 19:57 5K — produces an easy band near 7:52–9:26 per mile, marathon pace around 7:15, threshold at 6:51, and intervals at 6:10. All math runs in meters and seconds underneath, which is why the mile and kilometer columns never disagree.
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
Which race result should I enter?
A hard, recent effort anywhere from about 1.5 km up to a half marathon. The distance presets cover 5 km, 10 km, and 21.0975 km, and a well-paced 5K or 10K usually produces the steadiest VDOT. A result from last season will hand you paces your current fitness cannot back up — or has already outgrown.
What do the four zones mean in practice?
Each targets a different adaptation. The easy band builds the aerobic engine and should absorb most of your weekly mileage; marathon pace rehearses race-specific endurance; threshold raises the effort you can hold before fading sets in; and intervals at full aerobic power develop VO₂ max itself in short, hard reps.
My easy pace looks too slow — is that right?
Almost certainly yes. Easy running spans 59–74% of VO₂ max, and the slow end of that band still builds fitness. Runners who rush recovery days arrive at threshold and interval sessions too tired to hit them properly — and those sessions are where the pace gains actually come from.
Where is repetition (R) pace?
Left out deliberately. Daniels ties R pace to mile race speed because short, fast reps depend on mechanics and anaerobic power, which the VO₂-based model here does not describe. If you want R targets, work from a recent mile time instead of this table.
How can I sanity-check my threshold number?
Threshold sits at roughly 88% of VO₂ max, so VDOT 50 should read about 6:51 per mile (4:15 per kilometer). If the number looks nothing like what an honest tempo run feels like, the race you entered was probably not a true all-out effort — enter a better one.
Do the mile and kilometer paces ever disagree?
No. Each zone is computed once, in meters per second, and the two displays are formatted from that single value at the very end. Whichever unit your watch shows, both columns of the zone table describe the same physical speed.
How do these paces relate to heart rate zones?
They are two views of the same intensity scale. Pace targets are precise on flat ground in mild weather, while heart-rate training zones stay honest in heat and on hills where pace lies. Many runners pace their workouts and run recovery days by heart rate instead.
When should I recalculate my paces?
After any race that reflects a real change in fitness — in a steady block that often means every couple of months. As your VDOT score climbs, every zone tightens by a few seconds per mile, and training at the old paces quietly under-trains you.
Is this a substitute for coaching?
No. It is a pacing reference computed from one race and a published model. Heat, wind, fatigue, and sleep all move what the right pace is on a given day — let effort overrule the watch when the two argue, and bring the bigger questions to a coach.
These paces come from applying the Daniels model to a single race result, and no formula knows how today feels. Treat each zone as a starting target to adjust for weather, terrain, and recovery — general training information, not medical advice or a personal coaching plan.