Pace is the language of runners: “I ran a 9-minute mile”, “we’re aiming for 5:30 a kilometre”. Pace is simply time per unit of distance, and the calculation is easy but easy to get wrong when switching between miles and kilometres or between pace and speed. This calculator takes any distance and finishing time and returns the pace per mile and per kilometre, the speed in miles per hour and kilometres per hour, and predicted times for a 5K, 10K, half marathon and marathon using Riegel’s model of how performance changes with distance.
How to use the running pace calculator
- Enter the distance you ran in kilometres, miles or metres.
- Enter your time in hours, minutes and seconds.
- Read your pace per mile and per kilometre, and your speed.
- Check the predictions for other race distances to set goals.
Pace formulas
Pace per mile = pace per km × 1.609344
Speed = distance ÷ time (mph = 3,600 × metres ÷ seconds ÷ 1,609.344)
Riegel prediction: T₂ = T₁ × (D₂ ÷ D₁)1.06
The prediction model is from Riegel PS, Athletic records and human endurance, American Scientist 1981;69:285–290, which found that performance across distances from about 3.5 minutes to several hours follows a power law with an exponent near 1.06. The mile is 1,609.344 m, the half marathon 21,097.5 m and the marathon 42,195 m.
Worked example
You run 5 km in 25:00.
- Pace per km = 25:00 ÷ 5 = 5:00; per mile = 8:03
- Speed = 7.46 mph = 12.00 km/h
- Riegel predictions: 10K 52:07, half marathon 1:55:00, marathon 3:59:47
Treat the marathon figure as an upper limit of ability: it assumes endurance training equal to your 5K fitness.
Pace chart: finish times at common paces
| Pace per mile | Speed | km/h | Pace per km | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|---|---|---|
| 6:00 | 10.00 mph | 16.09 km/h | 3:44 | 18:38 | 37:17 | 1:18:39 | 2:37:19 |
| 7:00 | 8.57 mph | 13.79 km/h | 4:21 | 21:45 | 43:30 | 1:31:46 | 3:03:32 |
| 8:00 | 7.50 mph | 12.07 km/h | 4:58 | 24:51 | 49:43 | 1:44:53 | 3:29:45 |
| 9:00 | 6.67 mph | 10.73 km/h | 5:36 | 27:58 | 55:55 | 1:57:59 | 3:55:58 |
| 10:00 | 6.00 mph | 9.66 km/h | 6:13 | 31:04 | 1:02:08 | 2:11:06 | 4:22:11 |
| 11:00 | 5.45 mph | 8.78 km/h | 6:50 | 34:11 | 1:08:21 | 2:24:12 | 4:48:24 |
| 12:00 | 5.00 mph | 8.05 km/h | 7:27 | 37:17 | 1:14:34 | 2:37:19 | 5:14:38 |
Using pace in training
- Easy runs should feel conversational and are usually 1 to 2 minutes per mile slower than 10K race pace.
- Tempo and threshold runs are comfortably hard and near 10K to half-marathon pace.
- Use heart rate as well. Heat, hills and fatigue change the pace for a given effort; see the Heart Rate Zone Calculator and Zone 2 Heart Rate Calculator.
- Estimate energy. The Calories Burned Running Calculator converts pace and distance to calories.
Limits of the predictions
Riegel’s exponent is an average; trained marathoners may hold closer to 1.04 while those with limited mileage slow more steeply. Predictions across long gaps (5K to marathon) are optimistic unless you have trained for the longer distance. Course, weather, altitude and fuelling will change the real result. Related tools include the VO2 Max Calculator, Target Heart Rate Calculator and Steps to Miles Calculator.
This page is for information only and is not coaching or medical advice. If you have a heart condition or are new to hard exercise, check with a doctor before maximal efforts.
Sources
- Riegel PS. Athletic records and human endurance. American Scientist 1981;69:285–290.
- World Athletics. Competition rules: road race distances (half marathon 21,097.5 m; marathon 42,195 m).
- National Institute of Standards and Technology. NIST Handbook 44 (international mile = 1,609.344 m).
Frequently asked questions
How do I calculate running pace?
Divide your time by your distance. Running 5 km in 25 minutes is 25 ÷ 5 = 5:00 per kilometre, or 8:03 per mile. Pace per mile = pace per kilometre × 1.609344.
How are race times predicted?
The calculator uses Peter Riegel’s endurance model (American Scientist 1981;69:285–290): time over a new distance = known time × (new distance ÷ known distance)^1.06. The exponent reflects the slowdown over longer distances. It works best between similar distances, such as a 10K to a half marathon.
How accurate are the predictions?
They are a guide and assume equivalent training and conditions. Predicting a marathon from a 5K usually overestimates what an under-trained runner can do. Weather, course profile and fuelling all matter.
What pace should I run training in?
Easy runs are typically 1 to 2 minutes per mile slower than 10K race pace, but heart rate and effort are better guides. See the Zone 2 Heart Rate Calculator for easy-run heart rates.
What is a good running pace?
There is no standard. Recreational adult runners often run 9 to 12 minutes per mile (5:35 to 7:30 per km). Compare yourself with your own past results rather than others.