Running Split Calculator
Enter a race distance and goal time and get the split and cumulative clock time at every kilometre or mile, with an optional negative split. Print it, or write the checkpoints on your hand.
0 = even splits. The total time stays the same; the first half is slower by the same margin.
Average pace / mi
8:03
First mi
8:03
Last full mi
8:03
| Mile | Split | Cumulative |
|---|---|---|
| 1 | 8:03 | 8:03 |
| 2 | 8:03 | 16:06 |
| 3 | 8:03 | 24:08 |
| 4 | 8:03 | 32:11 |
| 5 | 8:03 | 40:14 |
| 6 | 8:03 | 48:17 |
| Finish (6.21) | 1:43 | 50:00 |
Example: 50:00 10K, even vs 3% negative
Same finish time. The negative-split version starts 5:08 per km and finishes 4:52 per km; the halfway clock is 25:23 instead of 25:00.
| Km | Even split | Even clock | 3% neg split | 3% neg clock |
|---|---|---|---|---|
| 1 | 5:00 | 5:00 | 5:08 | 5:08 |
| 2 | 5:00 | 10:00 | 5:06 | 10:14 |
| 3 | 5:00 | 15:00 | 5:05 | 15:19 |
| 4 | 5:00 | 20:00 | 5:03 | 20:22 |
| 5 | 5:00 | 25:00 | 5:01 | 25:23 |
| 6 | 5:00 | 30:00 | 4:59 | 30:22 |
| 7 | 5:00 | 35:00 | 4:57 | 35:19 |
| 8 | 5:00 | 40:00 | 4:56 | 40:14 |
| 9 | 5:00 | 45:00 | 4:54 | 45:08 |
| 10 | 5:00 | 50:00 | 4:52 | 50:00 |
Even-pace split table by goal time
Per-mile split for common goals. Multiply by the mile number for the clock time.
| Race | Goal | Mile split | Km split | Clock at halfway |
|---|---|---|---|---|
| 5K | 20:00 | 6:26 | 4:00 | 10:00 |
| 5K | 25:00 | 8:03 | 5:00 | 12:30 |
| 5K | 30:00 | 9:39 | 6:00 | 15:00 |
| 10K | 40:00 | 6:26 | 4:00 | 20:00 |
| 10K | 50:00 | 8:03 | 5:00 | 25:00 |
| 10K | 1:00:00 | 9:39 | 6:00 | 30:00 |
| Half | 1:30:00 | 6:52 | 4:16 | 45:00 |
| Half | 2:00:00 | 9:09 | 5:41 | 1:00:00 |
| Half | 2:30:00 | 11:27 | 7:07 | 1:15:00 |
| Marathon | 3:00:00 | 6:52 | 4:16 | 1:30:00 |
| Marathon | 4:00:00 | 9:09 | 5:41 | 2:00:00 |
| Marathon | 5:00:00 | 11:27 | 7:07 | 2:30:00 |
How the negative split is built
The calculator ramps pace linearly from (1 + k) × even pace at the start to (1 − k) × even pace at the finish, where k is the slider percentage. Integrated over the race that averages out to exactly the even pace, so the finish time is preserved, and the halves differ by 2k in pace. A linear ramp is a planning convenience; real races are run in flatter blocks (settle, hold, press), and the table is a target to be near, not a script to hit to the second.
Frequently Asked Questions
What is a split in running?
The time for one segment of a race -- usually each mile or kilometre -- as opposed to the cumulative clock time. A 50:00 10K at even pace has ten 5:00 km splits; the clock reads 5:00, 10:00, 15:00 and so on. Watches show both, which is where the confusion starts.
What is a negative split?
Running the second half of a race faster than the first. A 'positive split' is the reverse and is what happens by default when you start too fast. In this calculator a 2% negative split means the second-half pace is 2% quicker than even pace and the first-half pace 2% slower, so the total is unchanged.
How much of a negative split should I aim for?
1-3% for a road race; more than that and you left time on the table in the first half. On a track 5K or 10K, the very best performances are close to even with a fast last lap. The biggest wins come from avoiding a large positive split, not from engineering a large negative one.
Why does my watch's mile split not match the course markers?
GPS measures your path, which is longer than the certified shortest line, and the markers are placed on the certified line. Expect the watch to beep before the marker and for the gap to grow through the race. Plan from the markers.
These calculators use published exercise-science formulas and are for training guidance. They are estimates, not medical advice: if you have a heart condition or are starting exercise after a long break, talk to a doctor before training by heart rate or pace targets.