Running Pace Calculator: Pace, Time and Distance
Pace is time divided by distance. A 5K (3.11 miles) in 25:00 is 1,500 seconds ÷ 3.11 = 8:03 per mile, or 5:00 per kilometer.
Pace
8:03 /mi
Pace per km
5:00 /km
Speed
7.46 mph
Equivalent race times
| Race | Predicted time | Pace |
|---|---|---|
| 1 mile | 7:31 | 7:31 /mi |
| 5K | 25:00 | 8:03 /mi |
| 10K | 52:07 | 8:23 /mi |
| Half marathon | 1:55:00 | 8:46 /mi |
| Marathon | 3:59:46 | 9:09 /mi |
Show the math
- 1
Pace = time ÷ distance
25:00 = 1,500 s → 1,500 ÷ 3.1069 mi = 482.8 s/mi
Convert the time to seconds first so it can be divided.
= 482.8 s/mi
Read the steps as text
- Pace = time ÷ distance. 25:00 = 1,500 s → 1,500 ÷ 3.1069 mi = 482.8 s/mi Convert the time to seconds first so it can be divided.
- Back to minutes and seconds. 482.8 s ÷ 60 = 8 min 3 s
- Speed. 3.1069 mi ÷ 0.4167 h = 7.46 mph Speed is distance per hour, the inverse of pace.
- Predict other race times (Riegel's formula). T₂ = 25:00 × (42.195 ÷ 5)^1.06 = 3:59:46 for a marathon The 1.06 exponent accounts for slowing down over longer distances. Predictions are most reliable for distances close to the one you ran.
Pace, time and distance
Pace, time and distance are linked by one formula: pace = time ÷ distance. Know any two and you can find the third. The calculator converts times to seconds first, since minutes and seconds can't be divided directly, then converts the answer back to minutes and seconds.
Speed is the same information turned around: distance per hour instead of time per mile or kilometer. An 8:03 mile is about 7.46 mph, and a 5:00 kilometer is exactly 12 km/h.
Predicting race times
The table of equivalent times uses Riegel's formula, T₂ = T₁ × (D₂ ÷ D₁)^1.06, a widely used rule of thumb published by Peter Riegel in 1977. The exponent of 1.06 builds in the fact that runners slow down as distances get longer, so a 25-minute 5K predicts about 52:07 for 10K rather than exactly 50 minutes.
Predictions are most accurate between nearby distances and for runners trained for the longer race. Marathon predictions from a short race are often optimistic unless you've done the long training runs, so treat them as a target to test, not a promise.
Frequently asked questions
- What pace do I need for a 4-hour marathon?
- About 9:09 per mile, or 5:41 per kilometer. A marathon is 26.2 miles (42.195 km), and 4 hours is 14,400 seconds, so 14,400 ÷ 26.22 ≈ 549 seconds per mile.
- How long is a 5K, 10K and half marathon in miles?
- A 5K is 3.11 miles, a 10K is 6.21 miles, a half marathon is 13.1 miles and a marathon is 26.2 miles.
- How do I convert min/mile to min/km?
- Divide the pace in seconds by 1.609. An 8:00 mile (480 seconds) is 480 ÷ 1.609 = 298 seconds, or 4:58 per kilometer.
- How accurate are the race predictions?
- They're a good estimate for well-trained runners between nearby distances. Heat, hills, pacing and how well you've trained for the longer distance all make a big difference.