What is a negative split?

A negative split means running the second half of a race faster than the first half. For example, if you run a half marathon in 1:45:00 with a 2% negative split, you would run the first half in approximately 53:32 and the second half in 51:28. Most marathon world records have been set with a negative split strategy.

How much faster should the second half be?

A 1-3% negative split is typical and achievable for most runners. Elite marathon runners often aim for a 1-2% negative split. Larger splits (4%+) are harder to execute as they require significant restraint in the first half. Start conservative and build — the default 2% is a good target for most runners.

Why is negative splitting effective?

Starting conservatively preserves glycogen stores and reduces early lactate accumulation. Running even or positive splits often leads to significant slowing in the final third of a race. A negative split means you pass people in the second half which provides a psychological boost during the hardest part of the race.

RunCalcs

Negative Split Calculator

Calculate first and second half target splits for a negative split race strategy.

Race Distance

Select your race distance

Goal Hours

Hours component of goal time

Goal Minutes

Minutes component of goal time

Goal Seconds

Seconds component of goal time

How We Calculate This

This calculator divides your goal time into first and second half targets based on your chosen split percentage.

The formula

First half pace = Average pace x (1 + Split% / 2)

Second half pace = Average pace x (1 - Split% / 2)

A 2% split means the first half is 1% slower than average and the second half is 1% faster, giving a 2% total difference between halves.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always consult a coach or medical professional for personalised training advice.