Miss your goal pace by seconds a kilometer and you miss it by minutes at the finish. Plan your splits — and the strategy that avoids hitting the wall.
Marathon PacingLive
hit your goal time
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Race pace is simply your goal time divided by the distance, but how you distribute it matters. A negative split — starting conservatively and finishing faster — is how nearly every marathon world record is run, because going out too hard burns glycogen and invites the dreaded wall. Even pacing is the safe default.
Reading this result: Even pacing holds 5:41/km the whole way — the safe default, since pace is simply goal time (240 min) divided by distance (42.2 km).
Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.
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How it works
Race pace is the target time divided by the distance, but distribution decides the outcome. A negative split — starting controlled and finishing faster — is how nearly every marathon record is set, because going out too hard depletes glycogen and triggers the wall. This tool lays out per-kilometer splits for even, negative, and positive pacing.
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The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this marathon pace calculator tool really free?▾
Yes. Marathon Pacing runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?▾
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.