What are negative splits in running?

Negative splits mean running the second half of a race faster than the first. This is the most effective race strategy for most distances. It prevents early pace blowup and results in a stronger finish.

Should I run even splits or negative splits for a marathon?

For most recreational runners, slightly negative splits (running the second half 1-2 minutes faster) produce the best marathon results. Even splits are also excellent. Positive splits (slower second half) are usually a sign of going out too fast.

What variance percentage should I use for splits?

A 3% variance means the last km is 3% faster (negative) or slower (positive) than the first. For a marathon, 2-4% is a realistic target. Elite runners often use 1-2%.

Running Splits Planner

Race splits planner

Race distance

Goal finish time

Variance % (first vs last km)

Split strategy

km	Pace /km	Split	Cumulative
1	4:59	4:59	0:04:59
2	4:59	4:59	0:09:57
3	4:59	4:59	0:14:56
4	4:59	4:59	0:19:54
5	4:59	4:59	0:24:53
6	4:59	4:59	0:29:52
7	4:59	4:59	0:34:50
8	4:59	4:59	0:39:49
9	4:59	4:59	0:44:48
10	4:59	4:59	0:49:46
11	4:59	4:59	0:54:45
12	4:59	4:59	0:59:43
13	4:59	4:59	1:04:42
14	4:59	4:59	1:09:41
15	4:59	4:59	1:14:39
16	4:59	4:59	1:19:38
17	4:59	4:59	1:24:36
18	4:59	4:59	1:29:35
19	4:59	4:59	1:34:34
20	4:59	4:59	1:39:32
21	4:59	4:59	1:44:31
22	4:59	4:59	1:49:29
23	4:59	4:59	1:54:28
24	4:59	4:59	1:59:27
25	4:59	4:59	2:04:25
26	4:59	4:59	2:09:24
27	4:59	4:59	2:14:23
28	4:59	4:59	2:19:21
29	4:59	4:59	2:24:20
30	4:59	4:59	2:29:18
31	4:59	4:59	2:34:17
32	4:59	4:59	2:39:16
33	4:59	4:59	2:44:14
34	4:59	4:59	2:49:13
35	4:59	4:59	2:54:11
36	4:59	4:59	2:59:10
37	4:59	4:59	3:04:09
38	4:59	4:59	3:09:07
39	4:59	4:59	3:14:06
40	4:59	4:59	3:19:05
41	4:59	4:59	3:24:03
42	4:59	4:59	3:29:02
43	4:59	0:58	3:29:60

Analyse your training on Strava

Strava Premium unlocks advanced analytics, training plans, and segment comparisons.

Try Strava Premium

Even vs negative vs positive splits

Split strategy determines how you distribute your energy across a race. Research consistently shows that negative splits — running the second half faster than the first — produce optimal results for distances of 10K and above. World marathon records are almost always set with negative or perfectly even splits.

The danger of positive splits (going out fast and fading) is glycogen depletion and lactate accumulation. Once you exceed your lactate threshold in the opening miles, the resulting slowdown is disproportionate and usually unrecoverable.

Half marathon splits for common goal times

Goal time	Required pace	First 10K target	Last 11K target
1:30:00	4:16/km	43:00	47:00
1:45:00	4:58/km	50:00	55:00
2:00:00	5:41/km	57:00	1:03:00
2:15:00	6:23/km	1:04:00	1:11:00
2:30:00	7:06/km	1:11:00	1:19:00

Frequently asked questions

What are negative splits?

Negative splits mean running the second half faster than the first. This is the most effective strategy for most race distances and prevents early blowup caused by glycogen depletion.

Even or negative splits for a marathon?

Slightly negative (1-2 min faster second half) or perfectly even splits produce the best marathon results for most runners. Positive splits are usually the result of going out too fast.

What variance percentage should I use?

A 3% variance is realistic for most runners. 2% is elite-level precision. Use higher values (4–5%) if you tend to run significantly faster in the second half due to adrenaline management.