Pace is time per unit of distance: pace = time ÷ distance. Running 10 km in 50 minutes is a pace of 5:00 per km, or 8:03 per mile, a speed of 12 km/h (7.46 mph). Runners use pace rather than speed because it maps directly onto splits and race plans.
This calculator works both ways: enter a distance and time to get your pace, or a distance and target pace to get a finish time. It also shows what the same pace would give over a 5K, 10K, half marathon and marathon. Miles are converted with the exact international mile of 1,609.344 meters (NIST).
How to use the pace calculator
- Choose whether you want a pace or a finish time.
- Enter the distance and pick km, miles or meters.
- Enter the time as h:mm:ss or mm:ss (for example 1:45:30 or 50:00), or the target pace as mm:ss and whether it is per mile or per km.
- Read pace, time, speed and the race-distance table.
Formula
Race distances: 5 km, 10 km, half marathon 21.0975 km and marathon 42.195 km (26.22 mi).
Worked example
10 km in 50:00.
- Pace per km: 3,000 s ÷ 10 = 300 s = 5:00 per km.
- Pace per mile: 300 × 1.609344 = 482.8 s ≈ 8:03 per mile.
- Speed: 3,600 ÷ 300 = 12.00 km/h = 7.46 mph.
- The same pace over a marathon would be 3:30:59.
Target time mode: 8:00 per mile for a half marathon (13.11 mi) gives a finish of 1:44:53.
Using pace for training and racing
Equal-pace projections assume you can hold the same pace over longer distances, which is rarely true. Most runners slow as distance increases, so treat the marathon figure as an upper bound on speed, not a prediction. Plan even or slightly negative splits (a faster second half). Hills, heat and wind slow pace, so adjust by effort on those days.
Convert speeds between mph, km/h and m/s with the speed converter, and distances with the length converter. Longer sessions raise both calorie and fluid needs; see the tdee calculator and water intake calculator.
Treadmill speed to pace
Treadmills show speed, not pace. Pace is 60 divided by speed: minutes per mile = 60 ÷ mph, and minutes per km = 60 ÷ km/h.
| Speed | Pace | Speed | Pace |
|---|---|---|---|
| 5 mph | 12:00 /mi | 8 km/h | 7:30 /km |
| 6 mph | 10:00 /mi | 10 km/h | 6:00 /km |
| 7 mph | 8:34 /mi | 12 km/h | 5:00 /km |
| 8 mph | 7:30 /mi | 14 km/h | 4:17 /km |
| 9 mph | 6:40 /mi | 15 km/h | 4:00 /km |
| 10 mph | 6:00 /mi | 16 km/h | 3:45 /km |
For other speed units, the speed converter converts mph, km/h and m/s.
Race distances used here
The calculator uses the standard road-race distances: 5K = 5 km (3.107 mi), 10K = 10 km (6.214 mi), half marathon = 21.0975 km (13.109 mi) and marathon = 42.195 km (26.219 mi). Certified courses are measured along the shortest possible route, so the distance you actually run, and what a GPS watch records, is usually a little longer. If you are chasing a specific finish time, aim a few seconds per mile faster than the bare target pace.
Caveats and assumptions
- GPS watches often measure slightly more or less than the certified course distance, so pace may differ from official results.
- Equal-pace race predictions are not fitness predictions.
- Times are rounded to the nearest second.
Frequently asked questions
What pace is a 50-minute 10K?
5:00 per kilometer, or about 8:03 per mile.
How do I calculate running pace?
Divide total time by distance. 25:00 for 5 km is 25 ÷ 5 = 5:00 per km.
What pace do I need for a 4-hour marathon?
About 5:41 per km or 9:09 per mile, run evenly.
How do I convert pace per km to pace per mile?
Multiply the pace per km by 1.609344. 5:00/km × 1.609344 = 8:03/mile.
What pace is a 2-hour half marathon?
About 9:09 per mile or 5:41 per km.
Sources
- NIST SP 811 Appendix B.9 — Conversion factors — 1 mile = 1.609344 km; mph to m/s
- NIST — SI Units: Length — metric length units
This calculator gives general estimates for healthy adults and is not medical advice, diagnosis or treatment. Equations are averages and individuals differ. Talk to a qualified health professional before changing your diet, exercise or medication, and during pregnancy. See our disclaimer and how we build and check calculators.