Running pace calculator
Know two of time, distance and pace, and get the third. Miles and kilometers side by side.
How the math works
Pace is time divided by distance. A 1:55:00 half marathon is 6,900 seconds over 13.1094 miles, or 526 seconds per mile: 8:46/mi. Finish time is pace times distance, and distance is time divided by pace.
The race presets use the exact distances: 5,000 m, 10,000 m, 21,097.5 m for the half marathon and 42,195 m for the marathon, as World Athletics defines them. A mile is 1,609.344 m exactly (NIST Handbook 44). So a marathon is 26.2188 miles, not 26.2, and the difference is about 0.02 miles, or 10 to 15 seconds at most paces.
Results are rounded to the nearest second. Checkpoint times on the bib assume an even pace from start to finish. Your GPS watch usually measures a little long on race day because you can't run the tangents perfectly, so plan on a few seconds per mile of slack.
Estimates for planning. Weather, hills, course and fitness on the day all change the result. Formulas and distances reviewed October 21, 2026.