Last verified against the World Athletics Technical Rules (race distances) and NIST SP 811 (the mile).
Example: 5K in 25:00
Run each mile in 8:03, a speed of 7.5 mph, and you finish the 5K in 25:00. The table gives the clock time at each mile, at halfway and at the finish. Enter your own distance and time above to replace this example.
| Split | Clock time |
|---|---|
| 1 mile | 8:03 |
| Halfway1.55 miles | 12:30 |
| 2 miles | 16:06 |
| 3 miles | 24:08 |
| Finish3.11 miles | 25:00 |
Pace is time divided by distance: 25:00 ÷ 3.1069 miles = 8:03 per mile. 1 mile = 1.609344 km, an exact factor (NIST SP 811). We round each clock time to the nearest second.
How the pace calculator works
Your pace is your time divided by the distance. We use the race distances in the World Athletics rules, where the marathon is 42.195 km and the half marathon 21.0975 km. Measured in NIST's exact mile, the marathon is 26.2188 miles.
Your splits are your clock time at each mile or kilometer, at halfway and at the finish. We round each clock time to the nearest second, and the Finish row always matches your finish time.
An even split holds one pace from start to finish. A negative split runs the second half faster than the first by the gap you choose, and a positive split runs it slower. We cut the race into two halves of equal distance: the first half takes (finish time + gap) ÷ 2 and the second (finish time - gap) ÷ 2, each at a steady pace. If your finish time plus the gap comes to an odd number of seconds, rounding can leave the two halves one second off your gap.
Pace and speed turns one into the other: your pace is 60 minutes divided by your speed.
The calculator makes no allowance for hills, heat or wind.
Running pace questions
What is a negative split?
You run the second half of the race faster than the first. Pick Negative under Split strategy and enter how much faster you want the second half to be.
How do I wear the pace band?
Print it, cut along the dashed lines and wear it round your wrist or forearm under clear tape. It lists the clock time you want to see at each mile or kilometer marker.
Why did my watch say I ran further than the race distance?
Course measurers follow the shortest line a runner could take, so any wider line adds distance. World Athletics also recommends laying out road courses 0.1% long, so a course does not come up short when someone measures it again.
Sources
- World Athletics Technical Rules (Book C, C2.1)World Athletics, in force from 1 July 2026. Part VII Road Races: the standard race distances, including the marathon at 42.195 km.
- NIST Special Publication 811, Appendix B.8NIST, 2008 edition. 1 mile = 1.609344 km, an exact factor.
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