Negative Split Calculator
A negative split means running the second half of a race faster than the first. This planner splits your goal time into two halves, with the second half faster by the amount you choose.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
The first half is the goal time divided by two minus the chosen share, written as a decimal. The second half is whatever time is left, so the two always add back up to the goal.
Going out too fast is the usual mistake, so start the first half at the easy end of your plan. Half the time is not half the distance on a hilly course, so adjust the splits to the route.
Worked example
For a goal of 50 min, with a second half 2% faster, the first half is 25 min 15 s and the second half is 24 min 45 s.
Questions
How much faster should the second half be?
Many runners use a small gap, such as 1 to 3%. A big gap can be hard to hold at the end, so pick a number you can keep.
Does the same split work at any distance?
Yes. The method is the same for any distance, though the times are shorter for a shorter race.
Why not run the first half at goal pace?
Running the first half at goal pace leaves little room to speed up later. Starting a little slower gives you more to give at the end.
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