Convert a marathon goal into 800m interval times and pacing.
How runners use this tool
Yasso 800s remain popular because they offer a memorable marathon rule of thumb, but useful pages also explain that the workout is a heuristic, not a complete marathon predictor.
Enter your marathon goal time so the calculator can convert it into the matching 800-meter repeat target.
Review the repeat pace, recovery guidance, and suggested number of reps as a workout reference.
Use the result inside a broader marathon build rather than as a one-workout guarantee of readiness.
How to use the result
Treat strong Yasso sessions as encouraging evidence, not proof that marathon-specific endurance is fully built.
Combine the workout with long runs, marathon-pace sessions, and fueling practice for a more complete race forecast.
If the Yasso target feels achievable but long-run durability is not there, trust the long-run evidence more.
Formula and assumptions
Rule of thumb: a marathon goal of H:MM maps to an 800-meter repeat of M:SS.
Yasso 800s are best used as a heuristic workout rather than a strict physiological prediction model.
Marathon success still depends heavily on endurance, pacing, and fueling execution.
Worked examples
Beginner: 4:00 marathon goal → 4:00 per 800 m target. Creates a clear interval benchmark.
Race prep: Build from 4 to 10 reps → Progressive workout structure. Improves marathon-specific readiness over weeks.
Advanced: Strong Yasso but weak long runs → Use as one signal, not final predictor. Prevents overconfidence from a single session.