Running Split Calculator
Calculate per-kilometre or per-mile splits for any target race finish time.
Did this tool work for you?
How to use this calculator
Divide the target finish time (in seconds) by the total distance to get time per kilometre or mile. Convert to miles by multiplying km pace by 1.60934.
- 1
Select your race distance or choose "Custom" and enter it.
- 2
Enter your target finish time in hours, minutes, and seconds.
- 3
Choose whether to see your splits per kilometre or per mile.
- 4
Use the pace result to keep an even effort throughout the race.
Frequently asked questions
What does this calculator actually output?
One even pace, not a table of kilometre-by-kilometre times. It divides your target time in seconds by the distance in kilometres, then multiplies by 1.60934 for the per-mile figure. You get the pace in your chosen unit, the pace in both units, the distance and the finish time you entered, so you can read the splits off a watch or write your own pace band.
Which distances are built in?
The 5K and 10K are 5 and 10 km, the half marathon is 21.0975 km and the marathon is 42.195 km. For anything else choose Custom Distance and enter kilometres. A custom distance of 0 (the default) or a finish time of 0 returns a dash instead of a pace.
How do I enter a finish time?
Use the hours, minutes and seconds boxes together; they are added up, so 90 minutes and 1 hour 30 minutes are equivalent. Negative values and cleared boxes (which become 0) count as zero. The finish time is echoed back as h:mm:ss, or m:ss when under an hour.
Why can the same pace appear for different goals?
Paces are rounded to the nearest whole second. A half marathon in 1:45:00 works out to about 4:58.6 per km and shows as 4:59. A 3:30:00 marathon is exactly twice the time over exactly twice the distance, so it shows the same 4:59. The finish time shown is exactly what you entered, so the rounding only affects the displayed pace.
Does it account for hills, heat, aid stations or GPS error?
No. It assumes one constant pace over the stated distance. If you run extra distance by not following the shortest line, or slow down on climbs, your real average will differ from the figure shown. Treat the pace as a baseline and adjust by feel and by course profile.
Can it plan negative splits?
Not directly. It gives only the even-pace figure. To plan a faster second half, pick a pace slightly slower than the result for the first half and a pace slightly faster for the second, and check the two halves average back to your target.
Is the mile pace based on a true mile?
Yes, it converts using 1 mile = 1.60934 km. The distance field always reports kilometres to four decimals, even when you ask for splits per mile.
Running split calculator — turn a finish time into a race pace
The arithmetic behind a target pace
Pace is total time divided by distance. The calculator turns hours, minutes and seconds into one number of seconds, divides by the kilometres in the race, and rounds the result to a whole second per kilometre. The mile figure is the kilometre pace multiplied by 1.60934. Nothing else enters the calculation, so the same goal always produces the same pace. Entering 1 hour 45 minutes or 105 minutes in the minutes box gives an identical result, and the unit toggle only changes which pace is highlighted at the top.
Worked examples at common goals
Each row below was produced by running the calculator. The 5K entry shows why a time one second short of a round number still displays a round pace.
| Distance | Target time | Pace per km | Pace per mile |
|---|---|---|---|
| 10K | 50:00 | 5:00 | 8:03 |
| Half marathon | 1:45:00 | 4:59 | 8:01 |
| Marathon | 3:30:00 | 4:59 | 8:01 |
| 5K | 24:59 | 5:00 | 8:02 |
| 15 km (custom) | 1:15:00 | 5:00 | 8:03 |
Reading the result on race day
A 10K in 50:00 is 5:00 per kilometre, so you should pass the 5 km marker near 25:00. Multiply the pace by the marker number to build your own checkpoints, and allow a few seconds of drift in either direction. A watch that reads slightly long or short will move your numbers, and the marker on the course is the reference that counts.
Using the pace in training sessions
Your goal pace is a useful anchor for workouts. If the calculator says 5:00 per kilometre, a session of repeats at the goal pace shows how that effort feels over shorter pieces, and slower running in between sits comfortably on the other side of it. The calculator does not prescribe interval lengths or recovery, so choose those with a coach or a plan you trust.
What the number does not include
Elevation, wind, heat, crowds at the start, aid stations and the extra distance of corners all change real race pace, and the calculator models none of them. It is general running information rather than coaching or medical advice. Use it to set a clear reference, then let the course and your condition on the day decide how closely you follow it. If the first kilometres feel easy, resist the urge to bank time, because the pace shown is the average you need over the whole distance.
Learn more from an authoritative source:
CDCMarathon Time Predictor
Predict your marathon or half-marathon finish time from a recent race result using the Riegel formula.
Swim Pace Calculator
Calculate swimming pace per 100m, total swim time, or total distance in any open-water or pool event.
Cycling FTP Calculator
Estimate your Functional Threshold Power (FTP) from a test effort and calculate all 7 training power zones.
Training Volume Calculator
Calculate weekly training volume (sets × reps × weight) for up to 4 exercises and classify total volume.
Muscle Recovery Calculator
Estimate muscle recovery time based on training intensity, volume, age, and sleep quality.
Steps to Calories Calculator
Convert daily step count to estimated calories burned, distance walked, and active minutes.
Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →