Should I aim for a negative split?

It is the pattern of nearly every record, and it protects against the fade that ruins most amateur marathons. Even splits are a good target; going out fast almost never works.

Health & Fitnessfitness

Marathon Split Calculator

Marathon splits for even, negative or positive pacing. Almost every marathon record has been run on a negative or near-even split, and almost every amateur runs a positive one.

Also called: marathon pacing calculator, race split calculator.

First half

1:46:04

1:46:04 for the first half and 1:43:56 for the second, reaching 3:30:00 in total. That is 5:02 per km then 4:56 per km per km. A negative split is how nearly every record has been run and what most amateurs fail to achieve.

Second half

1:43:56

First half pace

5:02 per km

Second half pace

4:56 per km

Target time

3:30:00

At 10 km

50:16

At 30 km

2:29:55

Average pace

4:59 per km

On the strategy

A negative split is how nearly every record has been run and what most amateurs fail to achieve.

How this is calculated

Method and background

This is what the calculation gives for the numbers you entered. It is an estimate, not advice, and it knows nothing about your situation beyond those numbers. Rules for India change on a published schedule; the effective date is shown on every rule-based tool.

How this is calculated

The two halves must add to the target time, so a chosen split difference determines both. A negative split, running the second half faster, is what nearly every world record has been run on and what almost no amateur achieves: the common pattern is going out too fast and fading badly. Planning a modest positive split is realistic; planning an even one is ambitious; planning a large negative one usually means the first half was too slow rather than the second fast.

the two halves must sum to the target, so choosing a split fixes both

s: Split difference

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a 3:30 marathon on even splits

Target hours: 3
Target minutes: 30
Race distance: 42.2 km
Pacing strategy: Even splits
Split difference: 2 %

First half1:45:00

12,600 seconds halved

Open this example

a negative split runs the second half faster

Target hours: 3
Target minutes: 30
Race distance: 42.2 km
Pacing strategy: Negative split, second half faster
Split difference: 2 %

First half1:46:04

boundary: the halves still sum to 3:30

Open this example

Method and limits

What it assumes

A flat course. Elevation changes the sensible split considerably.

What it deliberately does not model

Course profile matters more than strategy on a hilly route.
Heat causes fade regardless of pacing discipline.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

Should I aim for a negative split?: It is the pattern of nearly every record, and it protects against the fade that ruins most amateur marathons. Even splits are a good target; going out fast almost never works.