Running Pace Calculator — Pace, Finish Time & Splits
Work out your pace per mile and per kilometre from a race time, or the finish time for a target pace, get checkpoint splits, and predict your times at other race distances with Riegel's formula.
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Even-Pace Splits
Elapsed time at each checkpoint if you hold the same pace the whole way.
| Checkpoint | Distance | Elapsed Time |
|---|
How this calculator works
- Pace = finish time ÷ distance · Finish time = pace × distance · Speed = distance ÷ time
- 1 mile = 1.609344 km. Race distances: 5K = 5 km, 10K = 10 km, half marathon = 21.0975 km, marathon = 42.195 km.
- Race prediction (Riegel, 1981): T₂ = T₁ × (D₂ ÷ D₁)1.06 — your time over a new distance, based on a recent race.
By Suhaib Hassan · Reviewed 28 September 2026 · How CalculatePilot verifies formulas →
A worked example
A 10K in 55:00 is 3,300 seconds ÷ 10 km = 330 s, or a 5:30 per km pace — 8:51 per mile and 10.9 km/h. Riegel's formula predicts a half marathon of 55:00 × (21.0975 ÷ 10)1.06 ≈ 2:01:21.
Using pace to plan a race
Splits let you check at each checkpoint whether you're on track for a goal time. Many runners train across several paces — easy conversational runs, tempo runs at a comfortably hard sustained pace, and intervals faster than race pace — rather than running every session at the same effort.
Race predictions assume similar training for the longer distance. They tend to be optimistic for the marathon unless you've done the long runs, and they don't account for heat, hills or course differences.
Sources
- Riegel PS. Athletic records and human endurance. American Scientist 1981;69:285–290.
- World Athletics — Book of Rules (road race distances)
Frequently asked questions
Why is my pace per mile a bigger number than my pace per km?
A mile is about 1.61 km, so it takes longer to cover at the same speed. Your pace per mile is always about 1.61 times your pace per kilometre.
How accurate are race time predictions?
Riegel's formula works well between similar distances for runners trained for both. The further apart the distances — for example predicting a marathon from a 5K — the more likely the prediction is too fast.
What's a good pace for a beginner?
There's no single number. Most beginners do best running at a conversational pace — one where you can speak in full sentences — and let speed come with consistent training.
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