Running Pace Calculator
Work out running pace, finish time or distance, with splits and race-time predictions.
m:ss, h:mm:ss or 1h 45m
Enter a finish time to see the result.
Works out any one of pace, finish time and distance from the other two, for the 5K, 10K, half marathon, marathon or any distance in km or miles. It gives the pace in both units and the speed for a treadmill, a split for every km or mile, even or with a negative split, a pace band to print, and predicted times at other race distances with Riegel's formula. Every calculation runs in your browser.
How to use it
Find picks the figure to work out; the other two are entered. Times and paces take 25:30 as minutes and seconds, 1:45:30 as hours, minutes and seconds, decimal seconds such as 3:26.5, unit forms such as 1h 45m, and a bare number as minutes. What was read shows under the field, so 25:30 reads “= 25 min 30 s”. Units sets the pace field, the custom distance and the splits to km or miles. Distances run from 0.1 to 1,000 km and times to 99 hours.
Negative split, from 0 to 5%, runs the second half that much faster than the first while the finish time stays the same. Print pace band prints the elapsed time at every split as one strip, to cut out and wear. The Exponent beside the predictions, from 1.01 to 1.15, sets how much a runner slows as the distance grows.
How it works
Pace is time divided by distance, and speed its inverse. A mile is exactly 1.609344 km, a half marathon 21.0975 km and a marathon 42.195 km. Times are kept to the fraction of a second and rounded to the second only where they are shown, so the last split ends exactly on the finish time.
With a negative split, the pace changes evenly from start to finish, so each split is a little faster than the one before and the second half averages the percentage faster than the first. A distance that does not divide into whole km or miles ends with a shorter split: a half marathon in miles is 13 splits and one of 0.11 mi.
Predictions use Peter Riegel's formula, which scales a time by the ratio of the distances raised to an exponent. 1.06 is the usual exponent; Riegel gave 1.08 for elite runners and 1.05 to 1.06 for male recreational runners aged 40 to 70. Predictions cover the standard distances within about 4 times the distance run, either way. A study of 2,303 recreational runners by Vickers and Vertosick found the formula well calibrated up to the half marathon, but its marathon times were 10 minutes or more too fast for about half of runners, so a marathon prediction from a shorter race is marked as often optimistic.
Pace = time ÷ distance; speed = distance ÷ time
Riegel: T₂ = T₁ × (D₂ ÷ D₁)^1.06
Examples
A half marathon under 2 hours
With Find set to Pace and a finish time of 1:59:59, the pace is 5:41 /km, or 9:09 /mi, at 10.6 km/h.
A marathon under 4 hours, with a 2% negative split
The first km takes 5:48 and the 42nd 5:35, and 21 km is passed in 2:00:39, as against 1:59:26 at even pace.
A 10K in 50:00, predicted further
Riegel's formula gives 5K 23:59, 15K 1:16:51, 10 miles 1:22:48, half marathon 1:50:19, marathon 3:50:01. The marathon figure is marked as often optimistic.
Pace chart for the half marathon and marathon
| Finish | Per km | Per mile | Speed |
|---|---|---|---|
| 1:30:00 | 4:16 /km | 6:52 /mi | 14.1 km/h |
| 1:40:00 | 4:44 /km | 7:38 /mi | 12.7 km/h |
| 1:45:00 | 4:59 /km | 8:01 /mi | 12.1 km/h |
| 1:50:00 | 5:13 /km | 8:23 /mi | 11.5 km/h |
| 2:00:00 | 5:41 /km | 9:09 /mi | 10.5 km/h |
| 2:15:00 | 6:24 /km | 10:18 /mi | 9.4 km/h |
| 2:30:00 | 7:07 /km | 11:27 /mi | 8.4 km/h |
| Finish | Per km | Per mile | Speed |
|---|---|---|---|
| 3:00:00 | 4:16 /km | 6:52 /mi | 14.1 km/h |
| 3:15:00 | 4:37 /km | 7:26 /mi | 13.0 km/h |
| 3:30:00 | 4:59 /km | 8:01 /mi | 12.1 km/h |
| 3:45:00 | 5:20 /km | 8:35 /mi | 11.3 km/h |
| 4:00:00 | 5:41 /km | 9:09 /mi | 10.5 km/h |
| 4:30:00 | 6:24 /km | 10:18 /mi | 9.4 km/h |
| 5:00:00 | 7:07 /km | 11:27 /mi | 8.4 km/h |
Rules and sources
At the four preset distances the calculator warns of a time faster than the world record, the fastest ratified mark on the road or track: 5K: 12:35.36, Joshua Cheptegei, 14 August 2020 (5000 m on the track); 10K: 26:11.00, Joshua Cheptegei, 7 October 2020 (10,000 m on the track); Half marathon: 57:20, Jacob Kiplimo, 8 March 2026 (half marathon); Marathon: 1:59:30, Sabastian Sawe, 26 April 2026 (marathon). Yomif Kejelcha's 56:51 half marathon of 23 August 2026 awaits ratification. Within the speeds Jones and Doust tested, about 10.5 to 18.0 km/h, the speed carries a note that a 1% treadmill incline matches the effort of running outdoors.
Sources
- World records, and the ratification notices of 23 July and 3 September 2026 — World Athletics
- Riegel PS. Athletic records and human endurance (American Scientist 1981;69(3):285–290) — American Scientist
- Vickers AJ, Vertosick EA. An empirical study of race times in recreational endurance runners (BMC Sports Sci Med Rehabil 2016;8:29) — BMC Sports Science, Medicine and Rehabilitation
- Jones AM, Doust JH. A 1% treadmill grade most accurately reflects the energetic cost of outdoor running (J Sports Sci 1996;14(4):321–327) — Journal of Sports Sciences
Reviewed
Frequently asked questions
See also
- Calorie Calculator — the calories you burn in a day, with your training.
- Time Calculator — add up the times of several runs.