The formula
Pace tells you how long one mile takes: pace = time ÷ distance. If you run a 5K (3.107 miles) in 31:04, which is 31.07 minutes, your pace is 31.07 ÷ 3.107 = 10.0 minutes per mile, or 10:00 min/mi. In kilometers the same run is 31.07 ÷ 5 = 6.21 minutes per kilometer, or about 6:13 min/km.
Watch the decimals: 0.5 minutes is 30 seconds, not 50. Multiply the decimal part by 60 to get the seconds.
Converting pace to mph – and back
Speed in mph = 60 ÷ pace in minutes per mile. A pace of 10:00 min/mi is 60 ÷ 10 = 6 mph. The other way around: pace = 60 ÷ mph. At 7.5 mph you run 60 ÷ 7.5 = 8 minutes per mile, or 8:00 min/mi.
For kilometers the same logic applies: 6:00 min/km is 60 ÷ 6 = 10 km/h. To switch between the two, one mile is 1.609 km, so 10:00 min/mi equals about 6:13 min/km.
Chart: pace and finish times
This is how long you need at an even pace for the common race distances (5K = 3.107 mi, 10K = 6.214 mi, half marathon = 13.109 mi, rounded to the second):
| Pace | mph | min/km | 5K | 10K | Half marathon |
|---|---|---|---|---|---|
| 8:00 min/mi | 7.5 | 4:58 | 24:51 | 49:43 | 1:44:53 |
| 9:00 min/mi | 6.7 | 5:36 | 27:58 | 55:55 | 1:57:59 |
| 10:00 min/mi | 6.0 | 6:13 | 31:04 | 1:02:08 | 2:11:06 |
| 11:00 min/mi | 5.5 | 6:50 | 34:11 | 1:08:21 | 2:24:12 |
| 12:00 min/mi | 5.0 | 7:27 | 37:17 | 1:14:34 | 2:37:19 |
The right pace for your goal
If you want to run a 5K in 30 minutes, you need a pace of 30 ÷ 3.107 = 9.66 minutes per mile, which is 9:39 min/mi (about 6:00 min/km). To break an hour for a 10K, you need the same 9:39 per mile or faster.
Many runners start out too fast and slow down at the end. Running evenly, or running the second half slightly faster, usually costs less energy.