Running Pace Calculator
Running pace calculator: distance and time into min per mile or min per km, a marathon or half marathon finish time at that pace, and the splits along the way.
Results
Assumptions and formula
Pace is time divided by distance. Speed is distance divided by time. A mile is exactly 1.609344 km. Target finish time scales in direct proportion to distance, holding pace constant.
Constant pace is arithmetic, not a prediction of endurance. Hills, fatigue, wind, stops and drafting can change running or cycling performance. Long distances use up to 100 equal split intervals.
Worked example
5 km in 25 minutes is 5:00 per km and 12 km/h. At exactly the same pace, 10 km takes 50 minutes. Enter a desired race distance and time to find the pace you need.
Race finish times by pace
Finish times for common race distances at an even pace, using the exact distances: a half marathon is 21.0975 km and a marathon 42.195 km.
| Pace | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|
| 4:00 /km (6:26 /mile) | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 5:00 /km (8:03 /mile) | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 6:00 /km (9:39 /mile) | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 7:00 /km (11:16 /mile) | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
| 8:00 /km (12:52 /mile) | 40:00 | 1:20:00 | 2:48:47 | 5:37:34 |
Holding the same pace over a longer race is much harder than the arithmetic suggests. Most runners slow as distance increases, so a 10K time does not translate directly into a marathon time; prediction formulas allow for that fade, and hills, heat and wind add more.
For race day, the table is most useful in reverse: pick a target time and read off the pace to hold. Starting slightly slower than target pace and finishing faster usually works out better than going out too fast.
Common mistakes to avoid
- Mixing up pace and speed. Pace is time per distance (minutes per km); speed is distance per time (km per hour). A lower pace number is faster.
- Assuming a 10K pace holds for a marathon. Most runners slow over longer distances, so a marathon target set from a short-race pace is usually too ambitious.
- Measuring with GPS alone. Watches often read slightly long or short, especially among tall buildings or trees, so a race course measured to the official distance can feel slower than training runs.
Frequently asked questions
Marathon pace calculator: what pace do I need to run a 4-hour marathon?
A 4:00 marathon over 42.195 km is 5:41 per kilometre, or 9:09 per mile, held from the start. For a half marathon in 2:00 the pace is the same, 5:41 per km, because the distance is exactly half. Most runners cannot hold a first-race pace evenly, so a plan built on slightly negative splits, a few seconds slower per kilometre in the first third, usually arrives closer to the target than an even schedule on paper. This calculator gives you the even splits and lets you adjust the pace to see what a slower start costs at the finish. The same page works as a marathon pace calculator for any target time, and for a half marathon or a 10K. The same arithmetic serves as a half marathon pace calculator, a min per mile calculator for treadmill settings, a cycling pace calculator in km/h or mph, and a race time predictor when you scale a recent result to a longer distance. It is a running calculator first, but the units do not care what you were doing.
Can I use this for cycling?
Yes. Average speed and constant-pace finish time use the same distance/time arithmetic for cycling and running. It does not model terrain or drafting.
Does doubling distance double my race time?
Only if you hold the same pace. The result is a planning scenario and does not account for fatigue or different race conditions.
Sources
Sources reviewed 15 September 2026: checked against their current editions on that date.
This page is an educational estimate and is not medical advice. Follow individual guidance from your clinician.