Pace Calculator
Free running pace calculator: pace per kilometre and mile, speed, and projected 5K, 10K, half and marathon finish times from any distance and time.
updated
- ✓ Runs in your browser — nothing uploaded
- ✓ No sign-up
- ✓ Free, no limits
| 5K | 25:00 |
| 10K | 50:00 |
| Half marathon | 1:45:29 |
| Marathon | 3:30:59 |
Projections assume you hold the same pace at every distance — real race times slow slightly as distance grows, so treat the longer projections as optimistic.
This pace calculator turns a distance and a finish time into your running pace — per kilometre and per mile — plus your speed and the finish times that pace projects for a 5K, 10K, half marathon and marathon. Pick a race distance or type your own, enter the time, and everything updates instantly.
The arithmetic is plain division, done properly: 10 km in 50:00 is 5:00 per kilometre, 8:03 per mile, 12 km/h — and would carry you through a half marathon in about 1:45:29 and a marathon in 3:30:59. Use it backwards on race day: to break four hours in a marathon you need 5:41 per kilometre or better.
One honest caveat is built into the table: equal-pace projections flatter you at longer distances, because real runners slow as distance grows — a 50-minute 10K usually predicts a marathon nearer 3:50 than 3:31. Treat the longer rows as best-case splits to pace against, not promises. Everything is computed in your browser; nothing is uploaded.
Frequently asked questions
How do I calculate my running pace?
Divide total time by distance: 50 minutes over 10 km is 5:00 per kilometre. The calculator does the fiddly part — converting to per-mile pace (multiply by 1.609) and to speed in km/h.
What pace do I need for a 4-hour marathon?
5:41 per kilometre (9:09 per mile) held for 42.195 km. For a 2-hour half marathon it's 5:41/km as well — the same pace over half the distance.
Can I predict a marathon from my 10K time?
Not by holding pace flat — everyone slows with distance. Race-prediction formulas (like Riegel's) add about 6% slowdown per doubling: a 50-minute 10K predicts roughly a 3:50 marathon, not the 3:31 that equal pace suggests.