Yasso 800s Marathon Calculator
Turn 800 m repeats into a marathon estimate, or back.
The Yasso 800s rule
Coach Bart Yasso’s shortcut: run repeats of 800 m on the track, and the average time you can hold for ten of them — in minutes and seconds — is roughly your marathon time in hours and minutes. Hit your 800s in 3:30 and the rule points to about a 3:30 marathon. This tool converts in either direction: from an 800 time to a marathon estimate, or from a marathon goal back to the 800 target.
How to run the workout
Build up to ten 800 m repeats at the target time, with a slow jog of equal duration between them — if your 800s are 3:30, jog 3:30 to recover. The session is meant to be run as a peak workout a few weeks out from race day, not a one-off time trial.
How much to trust it
Treat it as a fitness check, not a guarantee. The marathon depends on endurance, fuelling, heat, and pacing that a track workout cannot see, so many runners find Yasso a little optimistic. Pair it with the race time predictor and your long-run paces for a fuller picture.
Questions
What are Yasso 800s?
Bart Yasso’s rule of thumb: the average time you can run ten 800 m repeats in minutes and seconds roughly matches your marathon time in hours and minutes. 800s in 3:30 point to about a 3:30 marathon.
How do I run the workout?
Build up to ten 800 m repeats at the target time, jogging an equal duration between each. It is best done as a peak session a few weeks before race day, not a single time trial.
Is it accurate?
It is a useful fitness check but often optimistic, because the marathon depends on endurance, fuelling, and pacing a track workout cannot measure. Treat it as one data point alongside your long runs.