VDOT Calculator

What VDOT measures

VDOT comes from the work of Jack Daniels, one of the most influential distance-running coaches, and physiologist Jimmy Gilbert. In the 1970s they measured how much oxygen runners use at different speeds and how long people can hold a given share of their maximum. They published the results in 1979 as two equations, and VDOT is what you get when you put a race result through both.

The name comes from V̇O₂, the symbol for oxygen uptake. But VDOT is not a lab number. It is worked out from how fast you actually race, so it captures your running economy and race skill as well as your aerobic engine. That makes it a better guide to training paces than a lab VO₂max, which says nothing about how efficiently you run.

Take a runner who finishes a 5K in 25 minutes. That gives a VDOT of about 38, which corresponds to a 10K of around 51:54 and a half marathon of about 1:55:05. It also gives an easy pace of roughly 6:20–6:57 per km and a threshold pace near 5:16 per km.

The five Daniels training paces

Daniels built his system around five intensities. Each one trains something specific, and each has a sensible limit, so a week of training ends up as a mix of mostly easy running with small, controlled doses of the rest.

Easy (E)

The pace of warm-ups, recovery runs and most long runs. It should feel relaxed enough to hold a conversation. Easy running builds capillaries, heart strength and durability, and it should make up the large majority of your weekly distance. If you are not sure, go slower: there is no penalty for running easy days too easy.

Marathon (M)

Your predicted marathon race pace. Marathon-paced running teaches you the rhythm and fuelling of race day. A typical session is a long run with the last 8 to 15 km at M pace. Daniels suggests keeping a single M session to the lesser of about 29 km or 20% of your weekly distance.

Threshold (T)

Comfortably hard: the effort you could hold for about an hour in a race. Threshold work raises the speed you can sustain before fatigue builds quickly. Run it as a steady 20-minute tempo, or as cruise intervals such as 4 × 1.6 km with a minute of jogging between. Keep the total T running in one session to around 10% of your weekly distance.

Interval (I)

Hard running close to your VO₂max, held in work bouts of 3 to 5 minutes. A classic session is 5 × 1,000 m at I pace with jog recoveries of about the same duration. Daniels caps a single I session at the lesser of 10 km or 8% of weekly distance. These sessions are demanding; one a week is plenty for most runners.

Repetition (R)

Fast, short and relaxed: 200 m or 400 m reps with full recovery, for example 6–8 × 400 m with a 400 m walk or jog between. R pace improves speed and running form rather than fitness, so the focus is staying smooth. Keep a session to the lesser of 8 km or 5% of your weekly distance.

An example week at VDOT 38

Here is how those paces might fit into a week of about 40 km for the 25-minute 5K runner above, training for a 10K or half marathon. Notice how little of it is fast: 3.2 km at I pace and 20 minutes at T pace, both inside Daniels' limits for that weekly distance. Paces are per km.

Getting an accurate VDOT

• Use a race from the last six weeks or so. Older results do not reflect your current fitness.
• A 5K, 10K or half marathon gives the most useful number. Very short races flatter speed; marathons are affected by fuelling and pacing problems.
• Pick a flat course in mild weather. A hot, humid or hilly race gives a VDOT that is lower than your real fitness.
• It has to be an all-out effort. A training run or a race you jogged with friends will underestimate you.
• No recent race? Run a solo 5K time trial on a flat loop, or on a track early in the morning.

Using VDOT paces in Indian conditions

The equations assume cool air and a flat road. For much of the year in India, neither is true. On humid mornings in coastal cities, or in the pre-monsoon heat further inland, the same pace takes more effort, so hitting the numbers can turn an easy day into a hard one. Treat the paces as a ceiling and let effort, breathing or heart rate decide on those days.

Air quality matters too. In North Indian winters, move interval and repetition sessions indoors or onto a treadmill when the AQI is poor; the treadmill speeds in the calculator make that easy. And if you train at altitude, in places like Shimla or the Nilgiris, expect interval paces in particular to feel harder until you adapt.

VDOT chart: race times and training paces

Frequently asked questions

This is an independent calculator based on the equations published by Jack Daniels and Jimmy Gilbert in Oxygen Power (1979) and described in Daniels' Running Formula. It is not affiliated with Dr. Daniels or the VDOT O2 app.

Put your paces to work