Running Pace Calculator

What this tool does

The Running Pace Calculator solves for whichever value you are missing: pace from distance and time, finish time from distance and pace, or distance from time and pace. It converts between minutes per kilometre, minutes per mile, km/h and mph, lists even splits and predicts 1 mile to marathon times with Riegel's formula.

Pace is the language of running. Training plans prescribe it, race goals depend on it and watches display it, yet converting between finish times, minutes per kilometre and minutes per mile in your head is error-prone, especially for odd distances like the half marathon at 21.0975 km.

This calculator handles the three common questions. Give it a distance and time and it returns pace and speed; a distance and target pace and it returns your finish time; a time and pace and it returns distance. It then lists even splits for every kilometre or mile and uses Peter Riegel's 1981 formula, T2 = T1 × (D2 ÷ D1)^1.06, to predict equivalent performances over other race distances. Times accept h:mm:ss, mm:ss or plain minutes.

How to use Running Pace Calculator

1. Choose what to calculate: pace, finish time or distance.
2. Pick a race distance or choose Custom distance and enter it in kilometres, miles or metres.
3. Enter the time (for example 1:45:00) and/or the pace (for example 5:15).
4. Select whether pace and splits should be per kilometre or per mile.
5. Read pace, speed and time in the result cards.
6. Use the splits table for pacing bands or race wristbands and check the predicted times for other distances.

Tips for better results

• For a marathon, add 3 to 5 percent to a Riegel prediction from a half unless you have done long runs of 30 km or more.
• Courses measured to the shortest route mean GPS often shows 1 to 2 percent extra distance; aim slightly faster than goal pace on your watch.
• Use the per-mile splits for US races and per-kilometre splits for most of the rest of the world.

Common use cases

• Setting a target pace for a first 10K or half marathon.
• Converting a treadmill speed in km/h or mph into running pace.
• Planning splits for a parkrun personal best attempt.
• Estimating how far you ran from your time and average pace.

Common mistakes to avoid

• Typing 1.45 instead of 1:45:00; decimals are read as minutes, not hours and minutes.
• Assuming a 5K time predicts marathon fitness reliably without endurance training.
• Forgetting that hills, heat and wind make even-split pacing unrealistic on some courses.