Running Pace Calculator
Pace, speed and finish times for any distance, in both kilometres and miles.
Last updated
Your details
Result
- Pace
- 5:00 / km
- Speed
- 12.00 km/h
- Distance
- 10.000 km
- At this pace — 5K
- 25:00
- At this pace — 10K
- 50:00
- At this pace — half marathon
- 1:45:29
- At this pace — marathon
- 3:30:59
8:03 per mile
7.46 mph
6.214 miles
Formula — written step by step
10K in 50 minutes…
pace = time ÷ distance
pace = 3,000 seconds ÷ 10 km
pace = 300 seconds per km
pace = 5:00 / km
Pace is time per unit distance — minutes per kilometre or per mile. Speed is the same relationship inverted: distance per unit time. Runners think in pace; cyclists think in speed.
A worked example
What marathon does a 50-minute 10K predict?
- Distance
- 10 km
- Time
- 50:00
- Pace
- 5:00 / km
- 42.195 km × 5:00 per km
- = 210.975 minutes
3:30:59 — if the pace held
It will not. Pace degrades over distance, and most runners are one to two minutes per kilometre slower over a marathon than over a 10K. Treat the projection as a ceiling.
How to use this calculator
- Pick a standard race distance, or choose Custom and type your own.
- Enter your finish time in hours, minutes and seconds.
- Read your pace per kilometre and per mile, with the equivalent speed beside it.
- The split table shows the elapsed time at each kilometre, which is what you check your watch against.
Pace and speed are the same fact, inverted
Pace is time per distance; speed is distance per time. A 5:00 per kilometre pace and a 12 km/h speed describe an identical effort. Runners prefer pace because a watch showing 4:58 is directly comparable to a target, while 12.08 km/h is not.
The inversion matters when comparing improvements. Going from 6:00 to 5:00 per kilometre is a much larger gain than going from 4:00 to 3:30, even though the second looks like a bigger cut on the clock.
Race projections degrade with distance
The split times above assume you hold the same pace throughout, which nobody does across a longer race. Riegel's formula, the usual model, predicts that time scales with distance raised to about 1.06 — meaning doubling the distance costs rather more than doubling the time.
Use the projections as an upper bound on what you might run, then subtract for the distance you have not trained for.
Formula & methodology
What this calculator assumes
- Race projections assume the pace is held for the whole distance, which overstates performance over longer races — real times degrade with distance.
- One mile is taken as exactly 1.609344 kilometres; the half marathon as 21.0975 km and the marathon as 42.195 km.
- Split times are even. Most races are run with a deliberate negative or positive split rather than uniformly.
- Reading a projection as a target rather than a ceiling is the common mistake; Riegel's endurance model suggests time rises with distance to roughly the power 1.06.
Sources
- Riegel, P. S. (1981). Athletic Records and Human Endurance. American Scientist, 69(3), 285–290.
- Brueckner, J. C. et al. (1991). The energy cost of running increases with the distance covered. European Journal of Applied Physiology, 62(6), 385–389.
- Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291.
Frequently asked questions
What is a good 5K time?
It depends entirely on age, training and experience. Around 30 minutes is a common first-timer target, 25 minutes a solid recreational mark, and under 20 minutes competitive for most age groups.
Should I train at race pace?
Mostly not. The widely used approach puts around 80% of running at an easy conversational effort and the remainder hard, because easy volume builds the aerobic base that race pace depends on.
Why is my treadmill pace different outdoors?
A treadmill has no air resistance and its belt assists slightly. Setting a 1% incline is the usual compensation, and most runners find outdoor pace a little slower for the same effort.
Split times
| Distance | Elapsed |
|---|---|
| 1 km | 5:00 |
| 2 km | 10:00 |
| 3 km | 15:00 |
| 4 km | 20:00 |
| 5 km | 25:00 |
| 6 km | 30:00 |
| 7 km | 35:00 |
| 8 km | 40:00 |
| 9 km | 45:00 |
| 10 km | 50:00 |