Running Pace Calculator: Pace per Km and Mile, Plus Race Time Predictions
Short answer
Running pace is your time divided by the distance. A 10 km run in 50 minutes is a pace of 5:00 per km, or about 8:03 per mile, at 12 km/h. To predict a race time over another distance, the Riegel formula uses: new time = known time × (new distance ÷ known distance)^1.06.
Pace per km
5:37
min/km
Pace per mile
9:02
min/mi
Speed
6.6 mph
10.7 km/h
| Race | Predicted time |
|---|---|
| 5K | 28:04 |
| 10K | 58:31 |
| Half marathon | 2:09:06 |
| Marathon | 4:29:11 |
This running pace calculator turns a distance and a finish time into pace per kilometer, pace per mile and speed. It also predicts your times for the 5K, 10K, half marathon and marathon from that one result, using the Riegel formula.
Use a recent race or an all-out time trial for the predictions. An easy training run will give you predictions that are slower than what you could actually race.
How to use the running pace calculator
- 1
Enter the distance
Type the distance you ran and choose kilometers or miles.
- 2
Enter your time
Use hours, minutes and seconds (h:mm:ss). A 25-minute 5K is 0:25:00.
- 3
Read your pace and speed
You get pace per km, pace per mile, and speed in km/h and mph.
- 4
Check your predicted race times
The calculator projects your result to the 5K, 10K, half marathon (21.0975 km) and marathon (42.195 km).
How do you calculate running pace?
Divide your total time by the distance. The result is the time it takes you to cover one kilometer or one mile.
- Pace per km = time ÷ distance in km.
- Pace per mile = pace per km × 1.609 (one mile is 1.609344 km).
- Speed = distance ÷ time in hours, shown in km/h and mph.
Example: 10 km in 50:00 is 50 ÷ 10 = 5:00 per km. Per mile that is 5:00 × 1.609 ≈ 8:03, and the speed is 10 ÷ (50 ÷ 60) = 12 km/h, or about 7.5 mph.
How do you predict a race time?
The running pace calculator uses the Riegel formula: T2 = T1 × (D2 ÷ D1)^1.06, where T1 and D1 are your known time and distance and D2 is the race distance you want to predict.
The exponent 1.06 is slightly above 1, which means pace gets a little slower as the distance grows. From a 10K in 50:00, the formula predicts about 23:59 for a 5K, 1:50:19 for a half marathon and 3:50:01 for a marathon.
Predictions work best between nearby distances and for runners who have trained for the longer race. A marathon prediction from a 5K assumes you have the endurance to hold that pace for 42 km, which many runners don’t yet have, so treat long-distance predictions as a best case.
What is a good running pace?
A good running pace is one that fits the purpose of the run. There is no single good number, because it depends on age, experience and the distance.
- Easy runs: slow enough to hold a conversation. These are clearly slower than your race pace.
- Tempo runs: comfortably hard, close to the pace you could hold for about an hour.
- Intervals: around or faster than your 5K race pace, with recovery between repeats.
A useful habit is to compare your own pace over time on the same route or distance, instead of comparing with other runners.
How coaches use pace with clients
Personal trainers and online coaches use pace to set clear running targets and to track progress. A recent time trial gives the client’s current level, and the predicted race times show whether a goal like a sub-25-minute 5K is realistic.
- Set paces from a real result. Run a time trial, then base easy, tempo and interval paces on it instead of on a goal time.
- Retest every few weeks. A new time trial on the same course shows progress better than how a run felt.
- Balance running with strength work. Strength sessions for the legs and core fit around running weeks, not on top of the hardest days.
On the Coach+ coaching platform, you build training programs that mix runs with strength training, and clients log their workouts in your branded app. The AI assistant can draft a program that you review before sending, and weekly check-ins with progress photos keep you up to date on how training is going.
Frequently asked questions
How do I calculate my running pace?
Divide your time by the distance. 30 minutes for 5 km is 6:00 per km, or about 9:39 per mile.
What pace is a 25-minute 5K?
A 25-minute 5K is a pace of 5:00 per km, or about 8:03 per mile. The Riegel formula predicts about 52:07 for a 10K from that result.
How accurate are race time predictions?
They are estimates. The Riegel formula is most reliable between nearby distances and for runners trained for the longer race; marathon predictions from short races are often too optimistic.
How do I convert pace per km to pace per mile?
Multiply pace per km by 1.609. A 5:00 per km pace is about 8:03 per mile.
What pace should easy runs be?
Easy runs should be slow enough that you can hold a conversation, which is clearly slower than your race pace.
