Running Pace Calculator
Pace from a race time, plus Riegel predictions for 5K, 10K, half and marathon
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
If you held this fitness (Riegel 1.06)
Predictions assume similar conditions. Hills, heat and a different distance can move the time a lot.
Estimates only. Not medical advice and not a diagnosis. Talk to a clinician about your own numbers. Training advice is not a medical clearance to run.
About this tool
Pace is finish time divided by distance. Predictions for other distances use Riegel's formula with exponent 1.06: a 10K is a little slower than twice a 5K. Hills, heat, wind and a different training block will move the time. This is a training sketch, not a guaranteed race result and not a medical clearance to run. Estimates only.
How to use this tool
- Pick a distance or type custom kilometres5K, 10K, 15K, half, marathon and 1 mile are listed.
- Enter finish time as mm:ss or h:mm:ssExample: 22:30 or 1:45:00.
- Read min/km, min/mile and predicted timesUse predictions as a training sketch, not a race promise.
Key features
- Pace per kilometre and per mile from one finish time.
- Speed in km/h.
- Riegel predictions across common race distances.
- Custom kilometres when your loop is not a standard race.
Common uses
- Turning a 5K time into a min/km training pace.
- A first marathon prediction from a recent half.
- Comparing a watch's pace with a known loop time.
Tips for better results
- Predict from a recent all-out effort, not an easy jog.
- Add time for heat, hills and a first attempt at a new distance.
- Pair with heart-rate zone 2 for easy days so you do not race every run.
Mistakes to avoid
- Using a downhill 5K to predict a hilly marathon.
- Jumping distance too fast because the predictor looked kind.
- Ignoring injury pain because the pace "should" be easy.
Frequently asked questions
It depends on the runner. This tool converts your own time; it does not grade you against an age group.
Fatigue is not linear. Riegel's 1.06 exponent is a simple way to model that.
T2 = T1 times (D2 / D1) to the power 1.06. It is a widely used amateur predictor, not a physiological test.
Yes. It is free for normal use with no account required.
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