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Kilometres or miles. Race predictions use Riegel's formula.
Running Pace Calculator
Enter any two of distance, time and pace to get the third. You get pace in both min/km and min/mile, your speed, and predicted finish times for the 5K, 10K, half marathon and marathon.
-Pace per km
-Pace per mile
-Finish time
-Distance
-Speed
Riegel's formula (T2 = T1 × (D2 ÷ D1)^1.06) accounts for slowing down over longer distances. It works best for predictions up to about four times your input distance, with the right training.
The pace formulas
- Pace = time ÷ distance (for example, minutes per kilometre).
- Time = pace × distance.
- Distance = time ÷ pace.
- Speed = 60 ÷ pace in minutes (km/h or mph).
One mile is 1.609344 km, so a pace per mile is 1.609 times your pace per kilometre.
Worked example
A 10K in 55:00 is 55 ÷ 10 = 5:30 per km, or 8:51 per mile, which is 10.9 km/h. Riegel's formula predicts a half marathon of 55 × (21.0975 ÷ 10)^1.06 ≈ 2:01:21.
Using pace in training
Easy runs are usually 60 to 90 seconds per km slower than your 10K race pace. Tempo runs sit near the pace you could hold for about an hour. Use this calculator to turn a goal finish time into the pace to aim for on your watch, then check splits as you go.
Limitations
Hills, heat, wind and how well you fuel all change real race times. Race predictions assume you have trained for the longer distance; a fast 5K runner with no long runs will not hit the predicted marathon time.
Planning estimate only. Results use the list prices shown and may differ from your actual bill. Terms
Frequently asked questions
How do I calculate my running pace?
Divide your total time by the distance. A 10K in 55 minutes is 55 ÷ 10 = 5.5 minutes per km, which is 5:30 per km.
What pace do I need for a sub-2-hour half marathon?
About 5:41 per km or 9:09 per mile. Choose 'Finish time' mode, pick the half marathon, and adjust the pace until the time drops under 2:00:00.
How do I convert pace per km to pace per mile?
Multiply the pace per km by 1.609344. 5:00 per km becomes about 8:03 per mile.
How accurate are the race time predictions?
Riegel's formula is a well-known rule of thumb and is reasonable for trained runners when predicting up to a few times your input distance. Predictions for the marathon from a 5K are the least reliable.
What is a good 5K time for a beginner?
Many new runners finish a 5K in 30 to 40 minutes, a pace of 6:00 to 8:00 per km. Consistency matters far more than the number when you are starting out.