Pace calculator
Enter any two of distance, time and pace, get the third.
How do I calculate my running pace?
Divide the time by the distance: a 5K (3.107 miles) in 28:00 is 28 ÷ 3.107 = 9:01 per mile, or 5:36 per kilometer.
What pace do I need for a sub-4-hour marathon?
A marathon is 26.219 miles, so 4 hours needs 240 ÷ 26.219 = 9:09 per mile, or 5:41 per km. Run a few seconds faster to allow for crowds and turns.
How do I convert pace per mile to pace per km?
Divide by 1.609344: 10:00 per mile is 6:13 per km. To go the other way, multiply: 5:00 per km is 8:03 per mile.
How do I turn pace into speed?
Divide 60 by the pace in minutes: 10:00 per mile is 6 mph, 8:00 per mile is 7.5 mph — handy for setting a treadmill.
How long are the standard race distances?
5K = 3.107 miles, 10K = 6.214 miles, a half marathon = 13.109 miles (21.0975 km) and a marathon = 26.219 miles (42.195 km).
What time will I finish a 10K at an 8:30 mile pace?
52:49. A 10K is 6.214 miles, and 6.214 × 8:30 per mile comes to 52:49.
What pace is a 2:05 half marathon?
9:32 per mile (5:55 per kilometer), about 6.29 mph.
Is pace the same as speed?
They describe the same thing from opposite ends: pace is time per distance, speed is distance per time. Pace is used for running and swimming, speed for cycling and driving.
How the calculator works
Pace, distance and time are linked by one relation: time = distance × pace. Enter any two and the third follows: pace = time ÷ distance, distance = time ÷ pace. The calculator works internally in seconds and meters, with one mile defined as 1,609.344 m, so switching between miles and kilometers does not add rounding error. Speed is 3,600 divided by the pace in seconds per unit.
A worked example
A runner covers a half marathon (21.0975 km, 13.109 miles) in 2 hours 5 minutes, which is 7,500 seconds. Pace per mile is 7,500 ÷ 13.109 = 572.1 seconds, or 9:32. Per kilometer it is 7,500 ÷ 21.0975 = 355.5 seconds, or 5:55. The speed is 3,600 ÷ 572.1 = 6.29 mph.
Even pacing and splits
A constant pace is only an average. Most races have a slower first and last stretch, hills and turns, so the pace shown is the target for the whole distance, not for each segment. To check progress, convert the target into splits: multiply the pace by the split distance, such as the time per quarter mile on a track (a standard outdoor track is 400 m, about 0.249 miles).
Common mistakes
Entering a time as decimal minutes is a classic slip: 28.5 minutes is 28:30, not 28:50. Mixing a kilometer pace with a mile distance (or the reverse) is the other, and it is why the unit selector sits next to the distance. Also remember that a pace of 9:30 means nine minutes and thirty seconds, and rounding it to 9.5 minutes is fine only if you convert back correctly.
Sources: the international mile (exactly 1,609.344 m) from NIST Special Publication 811, and the standard race distances from World Athletics rules (marathon 42.195 km, half marathon 21.0975 km). Related: race time predictor, speed calculator, calories burned calculator and target heart rate calculator.