---
title: "Running pace calculator — free, runs in your browser"
description: "Pace, time and distance — give any two and get the third, with split times. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/pace-calculator/
site: "At One Place"
---

# Running pace calculator

Pace, time and distance — give any two and get the third, with split times.

## How it works

Give any two of pace, time and distance and this gives the third, plus splits for the standard race distances.

Pace is time per unit distance, which makes it inverted relative to speed: a lower number is faster. This is why pace arithmetic feels awkward — halving your pace figure means doubling your speed.

The equivalent-race predictions use Riegel’s formula, which scales time by distance raised to the power 1.06. It is reasonable for extrapolating between nearby distances, and increasingly optimistic the further you push it — predicting a marathon from a 5 km time will flatter almost everyone, because endurance at that range depends on training volume and fuelling rather than on speed alone.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### How do you calculate running pace?

Divide total time by distance. A 25-minute 5 km is 5:00 per kilometre, or about 8:03 per mile.

### How accurate are race time predictions?

Reasonable between nearby distances, optimistic across large gaps. Predicting a marathon from a 5 km flatters most runners, because long-distance performance depends on training volume and fuelling as much as on speed.

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## Sources

- Calculated on this page — At One Place (/about/)