Running Pace Calculator — 5K to Marathon
Pace, finish time or distance, with race predictions and splits
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Updated 2026-10-04The starting values (10 km in one hour) are an example. Replace them with your own run.
What do you want to find?
Distance unit
0.1 to 500 km. Use the buttons for race distances.
h:mm:ss (1:05:30) or mm:ss (45:20). A plain number is read as minutes.
Pace 6:00/km, finish 1:00:00
Result
- Pace
- 6:00 /km
- Finish time
- 1:00:00
- Speed
- 10 km/h
- Pace per mile
- 9:39 /mi
Predicted times for other distances
| Distance | Same pace | Riegel formula |
|---|---|---|
| 5K | 0:30:00 | 0:28:47 |
| 10K | 1:00:00 | 1:00:00 |
| Half marathon (21.0975 km) | 2:06:35 | 2:12:23 |
| Marathon (42.195 km) | 4:13:10 | 4:36:01 |
“Same pace” assumes you hold today’s speed the whole way. Riegel’s formula allows for slowing down over longer distances (T2 = T1 × (D2 / D1)^1.06). Marathon predictions depend heavily on training volume.
Splits (even pace)
| At | Elapsed |
|---|---|
| 1 km | 0:06:00 |
| 2 km | 0:12:00 |
| 3 km | 0:18:00 |
| 4 km | 0:24:00 |
| 5 km | 0:30:00 |
| 6 km | 0:36:00 |
| 7 km | 0:42:00 |
| 8 km | 0:48:00 |
| 9 km | 0:54:00 |
| 10 km | 1:00:00 |
Above 50 km the table steps every 5 km.
The math with your numbers
- Pace = 3,600 s / 10 km = 360 s/km (6:00)
- Speed = 3,600 / 360 = 10 km/h
Predictions are mathematical estimates. Weather, hills and training change real results. If you are building up to a long distance for the first time, increase it gradually.
Distances: half marathon 21.0975 km and marathon 42.195 km (World Athletics road race distances). Prediction formula: Riegel P.S., “Athletic records and human endurance,” American Scientist 1981;69(3):285-290.
What it is
The running pace calculator finds your pace per kilometre from a distance and time, your finish time from a target pace, or the distance you can cover in a given time at a given pace. It also shows speed in km/h and pace per mile, predicts 5K, 10K, half marathon and marathon times in two ways, and builds a split table with the elapsed time at every kilometre for race planning. It opens with 10 km in one hour as an example.
How to use
- Choose what to find: pace, finish time or distance.
- Fill in the other two fields. The buttons under distance insert 5K, 10K, half and marathon distances.
- Enter time as h:mm:ss or mm:ss and pace as m:ss. Switch the distance unit to miles to enter distance in miles and pace per mile; results then lead with miles too, and the split table steps every mile.
- Read pace, finish time, speed and the pace in the other unit.
- Use the prediction and split tables to plan your race.
How it works
- Pace (s/km) = time (s) / distance (km); time = distance × pace; distance = time / pace.
- Speed = 3,600 / pace in seconds; pace per mile = pace × 1.609344.
- Half marathon 21.0975 km and marathon 42.195 km (World Athletics road distances).
- Predictions: same pace = pace × target distance; Riegel = current time × (target / current distance)^1.06 (Riegel, American Scientist, 1981). No Riegel prediction is shown for runs under 1.5 km or shorter than 3:30.
- Splits assume an even pace, every kilometre, or every 5 km above 50 km. The last row is the actual distance.
- Calculations use exact seconds and are rounded to whole seconds once for display.
Examples
| Run | Pace | Half (same pace) | Half (Riegel) | Marathon (Riegel) |
|---|---|---|---|---|
| 10 km in 1:00:00 | 6:00/km | 2:06:35 | 2:12:23 | 4:36:01 |
| 10 km in 50:00 | 5:00/km | 1:45:29 | 1:50:19 | 3:50:01 |
| 5 km in 25:00 | 5:00/km | 1:45:29 | 1:55:00 | 3:59:47 |
Good to know
Predictions are mathematical estimates; weather, hills, fuelling and how you feel on the day all change real results. Marathon times in particular often come in slower than Riegel without enough long runs. For training intensity, try the heart rate zone calculator, and for energy use, the calories burned calculator.
FAQ
How is pace calculated?
Divide the time by the distance. 10 km in one hour is 3,600 s / 10 km = 360 s, or 6:00 per km, which is 10 km/h.
What pace do I need for a sub-2-hour half marathon?
The half is 21.0975 km, so 7,200 s / 21.0975 is about 341 s, meaning faster than 5:41 per km. Use the finish-time mode and try different paces.
Why are there two predictions?
The “same pace” figure assumes you hold today’s speed all the way. Riegel’s formula, T2 = T1 × (D2 / D1)^1.06, allows for slowing down over longer distances. Which one you end up closer to depends on training volume and the course.
How do I enter times?
Use h:mm:ss like 1:05:30 or mm:ss like 45:20. A plain number is read as minutes. Pace is m:ss, like 5:30.
Can I see pace per mile?
Yes, the result includes pace per mile (1.609344 km) for races or treadmills that use miles.
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