Race Equivalency Calculator

Predict your race time at any distance based on a recent performance. Uses the Riegel formula to calculate equivalent performances from 100m sprints to ultramarathons.

Reference Race Distance

Your 5K TimeMM:SS or H:MM:SS

VDOT = VO2(velocity) ÷ %VO2max(duration)

(Daniels & Gilbert, 1979 — every prediction inverts this equation numerically)

Enter a race time above to get your VDOT score and equivalent performances from 800m to the marathon. Or start from an example:

VDOT equivalencies assume you are equally trained for every distance. A miler's marathon prediction (and vice versa) is a ceiling, not a plan — trust the rows closest to your reference distance most.

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