Running Pace Calculator
Calculate pace per mile and kilometre, your speed, and predicted 5K, 10K, half marathon and marathon times.
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Quick Tip
Enter the distance you ran, or pick a standard race distance.
About This Tool
Why use Running Pace Calculator?
This running pace calculator converts a distance and finish time into pace per kilometre, pace per mile and speed, then uses the Riegel formula to predict what that performance is worth at other race distances.
Example: a 10K in 55:00 is 5:30 per kilometre, 8:51 per mile, and 10.9 km/h. Applying Riegel's exponent of 1.06, the same fitness predicts about 2:01:21 for a half marathon and 4:13:01 for a marathon.
Key Benefits
Riegel race predictions
Uses the standard endurance exponent of 1.06, which reflects the fact that pace slows predictably as distance grows.
Metric and imperial together
Pace per kilometre and per mile are shown side by side, which matters when your watch and your race use different units.
Works from any distance
Predict a marathon time from a parkrun, or check what a training run implies about your race fitness.
How to use Running Pace Calculator
- 1
Enter the distance you ran, or pick a standard race distance.
- 2
Enter your finish time in hours, minutes and seconds.
- 3
Read off pace per kilometre and per mile, plus your average speed.
- 4
Check the predicted times for 5K, 10K, half marathon and marathon.
Best use cases
Set a realistic goal pace for an upcoming race.
Convert a treadmill speed into your outdoor race pace.
Predict a marathon time from a recent half marathon.
Work out the pace you need to hold for a target finish time.
How this tool compares
Running Pace Calculator FAQs
How accurate are race time predictions?
The Riegel formula is reliable when the distances are close together and you are trained for the longer one. Predicting a marathon from a 5K usually reads optimistically, because the marathon depends on endurance and fuelling that a 5K never tests. Predictions from a half marathon are considerably more trustworthy.
What is the Riegel formula?
It predicts a time at a new distance as the known time multiplied by the ratio of distances raised to the power 1.06. The exponent above 1 encodes the fact that you cannot hold the same pace as distance increases — doubling the distance takes slightly more than double the time.
What is a good 5K time?
It depends entirely on age, sex and training history. Broadly, under 30 minutes is a solid recreational benchmark, under 25 minutes indicates regular training, and under 20 minutes is competitive for most age groups. Comparing against your own previous times is far more useful than comparing against averages.
Should I train at my race pace?
Only for part of your training. Most endurance programmes put the large majority of weekly volume at an easy conversational pace, with a smaller portion at threshold or race pace. Running every session at race pace is a common way to plateau or pick up an injury.
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