Running Pace Calculator
Distance plus time gives pace, or pace gives you a finish time, along with speed, per-kilometre splits and Riegel equivalent predictions.
How to Use
- Enter distance and time
Distance defaults to 10 km; write time as 50:00 (50 minutes) or 1:45:30 (1 h 45 min 30 s) — both are accepted.
- Or enter a pace
Once the pace field has a value the time field is ignored and the finish time is derived instead. To ask "how long is a half at 5:30?", fill only the pace.
- Read splits and predictions
The split table gives cumulative times per kilometre for checking race checkpoints; the prediction table gives equivalent times for four common distances, with an arrow on the current one.
FAQ
How accurate is the Riegel formula?
Within two to four times the original distance, for the same runner, the error is usually 1–3%. Beyond that it drifts: extrapolating 5 km to a marathon is typically 5–10 minutes optimistic, because a marathon also involves glycogen depletion and the wall, variables the formula ignores. It also assumes you prepared equally for both distances.
How do pace and speed relate?
Pace is minutes per kilometre, speed is kilometres per hour, and they are reciprocals: speed = 60 ÷ pace in minutes. 5:00/km is 12 km/h and 6:00/km is 10 km/h. Runners speak in pace, cyclists in speed.
Why is the last split different?
Because the distance is rarely a whole number of kilometres. Over 5.5 km the first five splits are one kilometre each and the sixth is 0.5 km, so its segment time is clearly shorter. Read the cumulative column for the clearer picture.
How do mile and kilometre paces compare?
One mile is 1.609344 km, so divide a mile pace by 1.609344 to get the kilometre pace. 5:00/mi is about 3:06/km and 8:00/mi about 4:58/km. Switching units recomputes automatically and shows the converted distance.