Endurometry
VDOT is fitted from a race with the 1979 oxygen-cost equations. A 10K in 48:30 is VDOT 41.5 — the same number the race predictor uses. Easy mid-pace is 6:11/km (59–74%); Threshold 5:04/km. It is not a laboratory VO2max and will not match the printed book tables to the second.
Last updated October 5, 2026
VDOT is the single number that ties the race time predictor to the training pace calculator. Same race, same VDOT, two jobs: scale to another distance, or map intensities for next week. How to use the zones in a week is training paces explained; this page is what the number is.
What VDOT is (and is not)
Jack Daniels and Jimmy Gilbert (1979, Oxygen Power) related running speed to oxygen cost and to the fraction of VO2max you can hold for a given time. A known race fixes:
v = distance (m) / time (min) // m/min
VO2 = −4.60 + 0.182258 v + 0.000104 v²
%VO2max = 0.8 + 0.1894393 e^(−0.012778 t)
+ 0.2989558 e^(−0.1932605 t) // t in minutes
VDOT = VO2 / %VO2max
VDOT is not laboratory VO2max. Two runners with the same 10K share a VDOT even if a lab test would disagree. It is an endurance index: useful for comparing performances and setting paces, not a medical measurement. Full equations: methodology.
The default race: 10K in 48:30 → 41.5
That is the calculator’s default and the same VDOT the predictor would report. Zones are published fractions of that VDOT, then inverted back to pace. Mid-pace is the middle of the band; the range is the slow and fast ends.
| Zone | % VDOT | Mid (min/km) | Range |
|---|---|---|---|
| Easy / Long | 59–74% | 6:11 | 5:41–6:48 |
| Marathon | 75–84% | 5:22 | 5:08–5:37 |
| Threshold | 83–88% | 5:04 | 4:57–5:11 |
| Interval | 95–100% | 4:33 | 4:28–4:39 |
| Repetition | 105–120% | 4:03 | 3:51–4:17 |
Marathon and Threshold overlap (83–84%) because the published bands overlap, not because of a bug. Easy should sit near the slow end until you know you recover. If “easy” is 5:22, you are in the Marathon band.
Why the book tables differ
Endurometry solves the published equations. The tables in Daniels’ Running Formula are rounded and interpolated. Differences of a few seconds per kilometre are expected. Do not chase the book to the second; chase the zone purpose. Easy / tempo / long in a week: easy vs tempo vs long.
Heart rate is a second language
Optional HR on the training-pace page is not derived from VDOT. It uses Tanaka HRmax (208 − 0.7 × age) and Karvonen reserve. Age 35, rest 55 → HRmax ≈ 184, Z2 ≈ 132–145 bpm. Heat and hills raise HR at the same pace; use a measured max on the heart-rate calculator when you have one.
Related Tools
Training Pace Calculator (VDOT Zones)
Get your VDOT from a recent race and see easy, marathon, threshold, interval and repetition pace zones plus heart-rate zones.
Race Time Predictor
Predict your finish time at any distance using the Riegel power law and the Daniels–Gilbert VO2max model.
Heart Rate Zone Calculator
Calculate your five running heart-rate zones from age, resting heart rate and max heart rate using the Karvonen method.
Related guides
Training Paces Explained
What easy, marathon, threshold and interval paces are for, how to derive them from a recent race, and why most runners do their easy runs too fast.
Easy, Tempo and Long Run Paces
One comparison table for the three intensities every plan is built from: easy, tempo and the long run — with heart-rate %, VDOT % and the pace range that goes with each.
How the numbers are calculated
Training paces (VDOT zones) · Race time prediction · Sources
Frequently Asked Questions
Is a higher VDOT always better?
On the same course and conditions, yes — it means a faster equivalent race. A downhill 5K inflates VDOT; do not treat that as fitness.
Which race should I enter?
A recent genuine race. A 10K or half is better than an easy long run. The models assume race effort.
Why don’t these paces match my watch’s “VO2 max”?
Watch estimates are a different product. VDOT here is only the 1979 race-fitted index.
Can I mix VDOT paces with 80/20?
Yes. Put ~80% of volume in Easy / Long (start slow in the 6:11 band for VDOT 41.5) and keep Threshold and Interval in the 20%.
Want a new tool or fix?
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