PACING GUIDE · EVEN, NEGATIVE AND POSITIVE SPLITS
Negative splits
A negative split means running the second half of a race faster than the first. For a 3:30:00 marathon, a gentle negative split is about 1:46:03 for the first half and 1:43:57 for the second, against 1:45:00 each at even pace. It is not a rule: a 2025 review found most record marathons were run at even or slightly negative pace, and that recreational runners usually slow down instead.
Even, negative and positive splits for the same 3:30:00 marathon
We read the top 5 US and UK results for “negative splits” on 24 September 2026. None of them compares all three pacing plans for the same goal while showing the formula. The only calculator in the top 5 truncates each split, so its 42 km row is 25 seconds off and the final 195 m takes 75 seconds. Here, every pacing plan ends at 3:30:00.
| Checkpoint | Even | Negative | Positive |
|---|---|---|---|
| 5 km | 0:24:53 | 0:25:19 | 0:24:27 |
| 10 km | 0:49:46 | 0:50:32 | 0:49:01 |
| 15 km | 1:14:39 | 1:15:37 | 1:13:41 |
| 20 km | 1:39:32 | 1:40:35 | 1:38:29 |
| 25 km | 2:04:25 | 2:05:26 | 2:03:24 |
| 30 km | 2:29:18 | 2:30:10 | 2:28:27 |
| 35 km | 2:54:11 | 2:54:47 | 2:53:36 |
| 40 km | 3:19:05 | 3:19:17 | 3:18:52 |
| Finish (42.195 km) | 3:30:00 | 3:30:00 | 3:30:00 |
A runner on the negative plan reaches 20 km 63 seconds behind the even plan, then makes up that time over the last 22.195 km. The plan changes pace steadily from 2% slower than average at the start to 2% faster at the finish, so the first half takes 50.5% of the goal time and the second 49.5%. That 2% is this site's illustrative preset, not a coaching standard.
How big is a “gentle” negative split at each distance?
With the same 2% preset, here is what each half looks like. The gap is always about 1% of the goal time, so you run the second half about 2% faster than the first.
| Race and goal | 1st half | 2nd half | Gap |
|---|---|---|---|
| 5K 0:25:00 | 0:12:38 | 0:12:22 | 16 s |
| 10K 0:50:00 | 0:25:15 | 0:24:45 | 30 s |
| Half marathon 2:00:00 | 1:00:36 | 0:59:24 | 72 s |
| Marathon 3:30:00 | 1:46:03 | 1:43:57 | 126 s |
The top pages quote examples from 0.6% to 4.3% and none gives a sourced rule, because there is no agreed figure. Use the table as a scale, not a target.
Do negative splits work?
A 2025 narrative review by Grivas in Frontiers in Physiology says that “a majority of record-breaking performances follow either an even or slight negative split profile”, that “recreational athletes tend to exhibit positive splits”, and that negative splits are “not universally applicable”. The proposed reasons are physiological: starting conservatively reduces “the risk of early glycogen depletion and excessive accumulation of lactate”. It is a review of earlier studies, not a new experiment.
The common mistake: banking or losing too much early
Every second you fall behind even pace by halfway has to be made up in the second half. If you run the first 21.0975 km of a marathon 10 seconds per km slower than even pace, you are 3:31 behind. To still finish on time, the second half must be 10 seconds per km faster than even pace: a 20-second-per-km swing between halves. In a 10K, running the first 5 km 5 seconds per km slower than even pace leaves you 25 seconds to make up. Hills and heat change the picture, and none of this is modelled here.
Even splits, and why constant pace is not constant effort
Even splits hold one pace from start to finish. On a flat course in steady weather that is close to even effort; on hills or into the wind it is not, which is why course-aware bands exist. Whole seconds also matter: a 49:35 10K is 297.5 seconds per km, so the kilometres alternate between 4:58 and 4:57 and each checkpoint stays within half a second of the exact time.
| Checkpoint | Segment | Pace /km | Elapsed |
|---|---|---|---|
| 1 km | 0:04:58 | 4:58 | 0:04:58 |
| 2 km | 0:04:57 | 4:57 | 0:09:55 |
| 3 km | 0:04:58 | 4:58 | 0:14:53 |
| 4 km | 0:04:57 | 4:57 | 0:19:50 |
| 5 km | 0:04:58 | 4:58 | 0:24:48 |
| 6 km | 0:04:57 | 4:57 | 0:29:45 |
| 7 km | 0:04:58 | 4:58 | 0:34:43 |
| 8 km | 0:04:57 | 4:57 | 0:39:40 |
| 9 km | 0:04:58 | 4:58 | 0:44:38 |
| 10K (10 km) | 0:04:57 | 4:57 | 0:49:35 |
Plan your own negative split
Enter your race and goal. The calculator starts on negative splits and shows even and positive alongside; the printed band uses whichever you pick. Average pace for the whole race stays 4:59 per km at 3:30:00 (8:01 per mile) whichever shape you choose.
Prints a 40 × 240 mm strip. Print at 100% (Actual size), then check the 50 mm ruler.
Even, negative and positive splits for 3:30:00
| Checkpoint | Even | Negative | Positive |
|---|---|---|---|
| 5 km | 0:24:53 | 0:25:19 | 0:24:27 |
| 10 km | 0:49:46 | 0:50:32 | 0:49:01 |
| 15 km | 1:14:39 | 1:15:37 | 1:13:41 |
| 20 km | 1:39:32 | 1:40:35 | 1:38:29 |
| 25 km | 2:04:25 | 2:05:26 | 2:03:24 |
| 30 km | 2:29:18 | 2:30:10 | 2:28:27 |
| 35 km | 2:54:11 | 2:54:47 | 2:53:36 |
| 40 km | 3:19:05 | 3:19:17 | 3:18:52 |
| Marathon (42.195 km) | 3:30:00 | 3:30:00 | 3:30:00 |
All three plans finish at 3:30:00; only the checkpoint times in between change.
Negative splits, every 5 km
| Checkpoint | Segment | Pace /km | Elapsed |
|---|---|---|---|
| 5 km | 0:25:19 | 5:04 | 0:25:19 |
| 10 km | 0:25:13 | 5:03 | 0:50:32 |
| 15 km | 0:25:05 | 5:01 | 1:15:37 |
| 20 km | 0:24:58 | 5:00 | 1:40:35 |
| 25 km | 0:24:51 | 4:58 | 2:05:26 |
| 30 km | 0:24:44 | 4:57 | 2:30:10 |
| 35 km | 0:24:37 | 4:55 | 2:54:47 |
| 40 km | 0:24:30 | 4:54 | 3:19:17 |
| Marathon (42.195 km) | 0:10:43 | 4:53 | 3:30:00 |
The 9 splits add up to exactly 3:30:00. The final 2.195 km is paced at 4:53 per km. Halfway (21.0975 km) at 1:46:03.
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
Marathon · 3:30:00
Negative splits · Continuous
| km | Time |
|---|---|
| 5 | 0:25:19 |
| 10 | 0:50:32 |
| 15 | 1:15:37 |
| 20 | 1:40:35 |
| 25 | 2:05:26 |
| 30 | 2:30:10 |
| 35 | 2:54:47 |
| 40 | 3:19:17 |
| 42.195 | 3:30:00 |
Elapsed time includes stops. Targets, not predictions. racepaceplanner.com
Overlap and tape here
Sources
- Grivas GV (2025), “The physiology and psychology of negative splits: insights into optimal marathon pacing strategies”, Frontiers in Physiology 16:1639816: quoted above.
- Wikipedia: Negative split: definition: second half faster than the first.
- World Athletics: marathon: 42.195 km.
Last checked 24 September 2026.