Running pace calculator
Free, from Runsei. No account, nothing stored on our side.
Pace, finish time or distance — put in the two you know and the third appears. Then take the splits for race day, in kilometres or miles, and choose how to run them: even, a negative split, or holding back early.
= 3:00:00
Nothing is sent anywhere. It updates as you type.
3:00:00 for 42.20 km is 4:16 per km — and 6:52 per mile.
Your splits
The same pace throughout — the pattern most consistently associated with better finishing times.
| Km | Split | Pace | Elapsed |
|---|---|---|---|
| Hold back. It should feel almost too easy. | |||
| 1 | 4:16 | 4:16 | 4:16 |
| 2 | 4:16 | 4:16 | 8:32 |
| 3 | 4:16 | 4:16 | 12:48 |
| 4 | 4:16 | 4:16 | 17:04 |
| 5 | 4:16 | 4:16 | 21:20 |
| 6 | 4:16 | 4:16 | 25:36 |
| Settle in. Comfortable, rhythm over speed. | |||
| 7 | 4:16 | 4:16 | 29:52 |
| 8 | 4:16 | 4:16 | 34:08 |
| 9 | 4:16 | 4:16 | 38:24 |
| 10 | 4:16 | 4:16 | 42:40 |
| 11 | 4:16 | 4:16 | 46:55 |
| 12 | 4:16 | 4:16 | 51:11 |
| 13 | 4:16 | 4:16 | 55:27 |
| 14 | 4:16 | 4:16 | 59:43 |
| 15 | 4:16 | 4:16 | 1:03:59 |
| 16 | 4:16 | 4:16 | 1:08:15 |
| 17 | 4:16 | 4:16 | 1:12:31 |
| 18 | 4:16 | 4:16 | 1:16:47 |
| 19 | 4:16 | 4:16 | 1:21:03 |
| 20 | 4:16 | 4:16 | 1:25:19 |
| 21 | 4:16 | 4:16 | 1:29:35 |
| Steady work. Controlled, no heroics yet. | |||
| 22 | 4:16 | 4:16 | 1:33:51 |
| 23 | 4:16 | 4:16 | 1:38:07 |
| 24 | 4:16 | 4:16 | 1:42:23 |
| 25 | 4:16 | 4:16 | 1:46:39 |
| 26 | 4:16 | 4:16 | 1:50:55 |
| 27 | 4:16 | 4:16 | 1:55:11 |
| 28 | 4:16 | 4:16 | 1:59:27 |
| 29 | 4:16 | 4:16 | 2:03:43 |
| 30 | 4:16 | 4:16 | 2:07:59 |
| 31 | 4:16 | 4:16 | 2:12:15 |
| 32 | 4:16 | 4:16 | 2:16:31 |
| 33 | 4:16 | 4:16 | 2:20:46 |
| Everything left. Run by effort, not by the watch. | |||
| 34 | 4:16 | 4:16 | 2:25:02 |
| 35 | 4:16 | 4:16 | 2:29:18 |
| 36 | 4:16 | 4:16 | 2:33:34 |
| 37 | 4:16 | 4:16 | 2:37:50 |
| 38 | 4:16 | 4:16 | 2:42:06 |
| 39 | 4:16 | 4:16 | 2:46:22 |
| 40 | 4:16 | 4:16 | 2:50:38 |
| 41 | 4:16 | 4:16 | 2:54:54 |
| 42 | 4:16 | 4:16 | 2:59:10 |
| 42.195 · final 0.195 | 0:50 | 4:16 | 3:00:00 |
What this can and cannot tell you
- It is arithmetic, so it is exactly right. Pace, time and distance are one equation. Nothing here is fitted, modelled or assumed about you.
- It does not know your course. Hills, wind, heat and corners all move a real split. A flat even-paced chart is a plan for a flat day.
- It does not know whether you can hold it. Any pace can be typed in. Whether it is yours for the whole distance is a different question, and a harder one.
Where the pacing advice comes from
An analysis of 78,912 Boston Marathon finishers found even pacing to be the most common pattern and the one most consistently associated with better finishing times — runners in the strongly positive-split group finished on average about an hour slower. Variable pacing was associated with hitting the wall in 85% of cases, against almost none among even-paced runners.
Pacing strategy patterns and performance in marathon running (PLOS ONE, n=78,912)
A small negative split is what most published advice describes, and there is a physiological case for it — better glycogen use early, less metabolic cost carried into the closing miles. The 2% is a convention rather than a measured optimum, and the size that matters most is the one you can actually hold.
Pace, time and distance are one equation with three arrangements. There is no model here, nothing fitted, and nothing assumed about you — which is why this tool, unlike a training plan, cannot be wrong about anything except your typing.
Do you know your paces?
Five finish times, fast and slow. Guess the pace each one needs. Everyone gets the same five today, and nothing is sent to us.
Getting today’s five…
A pace is easy. Knowing which one is yours is not.
This page will happily give you the splits for a time you cannot run. Working out what you can run — from what you have actually been doing, and keeping it honest as that changes — is the part we are building.
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Race pace for common targets
The pace you need to hold, even from start to finish, for some finish times people ask about. Type the same numbers into the calculator above for the full split chart.
| Target | Per kilometre | Per mile |
|---|---|---|
| 5K in 25:00 | 5:00 | 8:03 |
| 10K in 50:00 | 5:00 | 8:03 |
| Half marathon in 2:00:00 | 5:41 | 9:09 |
| Marathon in 4:00:00 | 5:41 | 9:09 |
How pace, time and distance fit together
They are one equation with three arrangements. Pace is time divided by distance; time is pace multiplied by distance; distance is time divided by pace. Everything on this page is one of those three, which is why it can be exactly right in a way that a training plan or a race prediction never can be.
Reading a split chart
Each row is one kilometre or one mile: how long that piece takes, the pace it represents, and the clock at the end of it. The last row of a marathon is the odd 195 metres, so its split looks tiny while its pace is the number to read.
Even, negative or positive
An analysis of 78,912 Boston Marathon finishers found even pacing to be both the most common pattern and the one most consistently associated with finishing well — the strongly positive-split group finished on average about an hour slower, and hit the wall far more often. A slight negative split is the other defensible choice and has a reasonable physiological case behind it. The positive option is here because it is what a lot of people actually run, not because we are recommending it.
Holding back early
This is not a research finding, it is a guard rail: the opening fifth about 3% easier than goal pace, goal pace through the middle, and a little quicker at the end. It is there for the runner who knows the first kilometres will feel too easy and go out too fast. Every plan adds up to your finish time exactly.
Kilometres and miles
A mile is 1609.344 metres exactly, and this page converts with that number rather than a rounded 1.61 — over a marathon the difference is small but it is the kind of small that shows up in a finish-time estimate.
What a pace chart is not
It is not a prediction and it is not a plan. It will give you the splits for a two-hour marathon as cheerfully as for a five-hour one. Whether the pace is yours, and whether the course and the day will let you hold it, are questions no amount of division can answer.