Pace, speed and time
Runners talk in pace, minutes per mile or per kilometer, while treadmills show speed in miles per hour. Both come from the same two numbers: distance and time. This calculator converts a finish time into pace and speed, and predicts your time over other race distances.
The formulas
- Pace per mile = time ÷ distance in miles.
- Pace per kilometer = time ÷ distance in kilometers (1 mile = 1.609 km).
- Speed (mph) = distance in miles ÷ time in hours.
- Race prediction (Riegel): T2 = T1 × (D2 ÷ D1)^1.06. The exponent 1.06 accounts for slowing down as distance grows.
Worked example: a 55 minute 10K
- Distance: 6.214 miles.
- Pace: 55:00 ÷ 6.214 = 8:51 per mile, or 5:30 per km.
- Speed: 6.214 ÷ 0.9167 h = 6.78 mph.
- Predictions: 26:23 for a 5K, 2:01:21 for a half marathon and 4:13:01 for a marathon.
Pace by 10K finish time
| 10K time | Pace per mile | Pace per km | Predicted marathon |
|---|---|---|---|
| 40:00 | 6:26 | 4:00 | 3:04:00 |
| 45:00 | 7:15 | 4:30 | 3:27:01 |
| 50:00 | 8:03 | 5:00 | 3:50:01 |
| 55:00 | 8:51 | 5:30 | 4:13:01 |
Common pace goals
| Goal | Pace per mile | Pace per km |
|---|---|---|
| 30 min 5K | 9:39 | 6:00 |
| 25 min 5K | 8:03 | 5:00 |
| 1 h 10K | 9:39 | 6:00 |
| 2 h half marathon | 9:09 | 5:41 |
| 4 h marathon | 9:09 | 5:41 |
| 3 h marathon | 6:52 | 4:16 |
How reliable are predictions?
Riegel’s formula works best between 5K and the half marathon, and when you have trained for the target distance. Marathon predictions are often optimistic for runners without regular long runs of 16 to 20 miles. Heat, hills and wind also slow you down: use a recent race on a similar course as your input.
Using pace in training
- Easy runs: 1 to 2 minutes per mile slower than your 10K pace. Most of your weekly miles should feel conversational.
- Tempo runs: around your half marathon pace, held for 20 to 40 minutes.
- Intervals: around your 5K pace or faster, in repeats of 400 m to 1 mile.
The VO2 max calculator gives training paces from a 12-minute test or your resting heart rate.
Treadmill tip
Treadmill speeds are in mph. To run a pace of 9:00 per mile, set 60 ÷ 9 = 6.7 mph. A 1% incline roughly makes up for the lack of air resistance outdoors.