HALF MARATHON SPLIT CALCULATOR · 21.0975 KM
Half marathon split calculator
Enter your goal to get a split for every mile, kilometre or 5 km mat, ending exactly on your finish time. A 2:00:00 half marathon at even pace is 9:09 per mile (5:41 per km): 5 km in 0:28:26, 10 km in 0:56:53, mile 13 at 1:59:00, and the last 1.0975 km from the 20 km mat takes 6:15.
Prints a 40 × 240 mm strip. Print at 100% (Actual size), then check the 50 mm ruler.
Even, negative and positive splits for 2:00:00
| Checkpoint | Even | Negative | Positive |
|---|---|---|---|
| 5 km | 0:28:26 | 0:28:52 | 0:28:00 |
| 10 km | 0:56:53 | 0:57:29 | 0:56:17 |
| 15 km | 1:25:19 | 1:25:49 | 1:24:50 |
| 20 km | 1:53:45 | 1:53:53 | 1:53:38 |
| Half marathon (21.0975 km) | 2:00:00 | 2:00:00 | 2:00:00 |
All three plans finish at 2:00:00; only the checkpoint times in between change.
Even splits, every 5 km
| Checkpoint | Segment | Pace /km | Elapsed |
|---|---|---|---|
| 5 km | 0:28:26 | 5:41 | 0:28:26 |
| 10 km | 0:28:27 | 5:41 | 0:56:53 |
| 15 km | 0:28:26 | 5:41 | 1:25:19 |
| 20 km | 0:28:26 | 5:41 | 1:53:45 |
| Half marathon (21.0975 km) | 0:06:15 | 5:42 | 2:00:00 |
The 5 splits add up to exactly 2:00:00. The final 1.0975 km is paced at 5:42 per km. Halfway (10.54875 km) at 1:00:00.
Print at 100% (Actual size) with headers and footers off. The strip is 40 × 240 mm. Measure the 50 mm ruler before cutting; if it is not 50 mm, your printer rescaled the page. Tape it loosely around your wrist.
RACE PACE PLANNER
Half marathon · 2:00:00
Even splits · Continuous
| km | Time |
|---|---|
| 5 | 0:28:26 |
| 10 | 0:56:53 |
| 15 | 1:25:19 |
| 20 | 1:53:45 |
| 21.0975 | 2:00:00 |
Elapsed time includes stops. Targets, not predictions. racepaceplanner.com
Overlap and tape here
Three ways to pace the full 21.0975 km
We checked the top 5 US and UK results for “half marathon split calculator” on 24 September 2026. They offer even pacing only, and one calculator uses 21.1 km, so 5:00 per km shows 1:45:30 instead of 1:45:29. None gives 5 km mat splits or times the stretch after mile 13 on its own. The calculator above does all of that, side by side for even, negative and positive pacing.
What is a good split for a half marathon?
Even or slightly negative is the usual target. The 2025 review cited below found that record marathons were mostly run at even pace or with a slight negative split, while recreational runners tended to slow down. This site's negative preset turns a 2:00:00 goal into 1:00:36 for the first half and 0:59:24 for the second, a 72-second difference. Treat it as one option to compare, not a prescription.
How the splits are calculated
Even splits give each segment time in proportion to its length. Negative splits start 2% slower than average and speed up steadily to finish 2% faster; positive splits do the reverse. Every checkpoint is the exact elapsed time rounded to the nearest second, so the last split always matches your goal. The 2% is an illustrative preset chosen for this site. Hills, heat and wind are not modelled.
Sources
- World Athletics: half marathon: 13.1094 miles or 21.0975 km.
- NIST: unit conversion factors: 1 mile = 1.609344 km exactly.
- Grivas GV (2025), Frontiers in Physiology 16:1639816: review of negative-split pacing.
Last checked 24 September 2026.