Should I run even or negative splits?

Even, unless you are experienced. An even effort produces close to an even pace on a flat course and it is the plan most amateur runners execute best. Negative splitting is optimal in theory and demands the discipline to feel slow for the first half, which is exactly what most people cannot do on a start line.

How much slower should the first half be for a negative split?

One to two percent is plenty, which over a marathon is about a minute across the first half. Runners who plan a four percent negative split usually end up running an even race and feeling like they failed at something.

Why do most runners positive split?

Because goal pace feels easy in the first few miles when you are fresh, tapered and surrounded by people. Twenty seconds a mile banked early typically costs about four times that at the end. It is the single most common way a goal race is lost.

Should I adjust splits for hills?

Yes, by effort rather than by pace. On a rolling course, hold your effort steady and let the pace vary, then check the cumulative time at the flat sections. Chasing a fixed pace up a climb early in a race is expensive out of proportion to the time it saves.

Free tool · Splits

Race Split Calculator

Enter a goal time and get every split between the start and the finish, in miles or kilometres. Even pacing, a controlled negative split, or the positive split that happens to people who go out too fast.

RaceGoal timeType the digits. 33000 becomes 3:30:00.

Strategy

The same pace throughout. The simplest plan and the one that wins most amateur races.

Average pace

8:01/mi

Halfway at 1:52:08.

Splits

1 mi
8:01/mi
8:01
2 mi
8:01/mi
16:01
3 mi
8:01/mi
24:02
4 mi
8:01/mi
32:02
5 mi
8:01/mi
40:03
6 mi
8:01/mi
48:03
7 mi
8:01/mi
56:04
8 mi
8:01/mi
1:04:05
9 mi
8:01/mi
1:12:05
10 mi
8:01/mi
1:20:06
11 mi
8:01/mi
1:28:06
12 mi
8:01/mi
1:36:07
13 mi
8:01/mi
1:44:07
14 mi
8:01/mi
1:52:08
15 mi
8:01/mi
2:00:09
16 mi
8:01/mi
2:08:09
17 mi
8:01/mi
2:16:10
18 mi
8:01/mi
2:24:10
19 mi
8:01/mi
2:32:11
20 mi
8:01/mi
2:40:11
21 mi
8:01/mi
2:48:12
22 mi
8:01/mi
2:56:13
23 mi
8:01/mi
3:04:13
24 mi
8:01/mi
3:12:14
25 mi
8:01/mi
3:20:14
26 mi
8:01/mi
3:28:15
Finish (26.22 mi)
8:01/mi
3:29:60

Print these, write them on your arm, or set them as watch alerts. The second column is the pace for that segment, the third is your elapsed time at that marker.

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These numbers are the first 30 seconds of what Shed does.

Shed reads your Apple Health, grounds your VDOT in your actual training — not one race — and writes the whole block: every workout, every pace, adjusted as life happens. The calculator gives you a snapshot; Shed gives you the plan.

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How to use a split table

The point of a split table is not to hit every number. It is to know, at any marker, whether you are ahead or behind, and by how much, without doing arithmetic while oxygen-deprived. Write the elapsed times on your arm or set them as lap alerts.

The most useful markers are the ones you will actually check. For a marathon that is usually 10K, halfway, 30K and 20 miles. Everything between those is noise you should not be reacting to.

The first 10 percent rule

Whatever your goal pace, run the first 10 percent of the race slightly slower than it. Ten to fifteen seconds per mile in a marathon, three to five seconds per kilometre in a 10K. You will feel like you are wasting the taper. You are not.

The energy cost of running faster than goal pace early is disproportionate, and the time it banks is smaller than the time it costs later. Almost nobody has finished a race wishing they had gone out harder.

Frequently asked

Should I run even or negative splits?: Even, unless you are experienced. An even effort produces close to an even pace on a flat course and it is the plan most amateur runners execute best. Negative splitting is optimal in theory and demands the discipline to feel slow for the first half, which is exactly what most people cannot do on a start line.
How much slower should the first half be for a negative split?: One to two percent is plenty, which over a marathon is about a minute across the first half. Runners who plan a four percent negative split usually end up running an even race and feeling like they failed at something.
Why do most runners positive split?: Because goal pace feels easy in the first few miles when you are fresh, tapered and surrounded by people. Twenty seconds a mile banked early typically costs about four times that at the end. It is the single most common way a goal race is lost.
Should I adjust splits for hills?: Yes, by effort rather than by pace. On a rolling course, hold your effort steady and let the pace vary, then check the cumulative time at the flat sections. Chasing a fixed pace up a climb early in a race is expensive out of proportion to the time it saves.

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