# FAQ: Race time splits

### What are negative splits and positive splits?

If you run *negative splits* this means that you run the second half
of the race quicker than the first.
*Positive splits* means that you run the second half slower than the first.

### Should I aim for negative splits?

Probably, yes. Most athletes perform better if they run the second half of a race slightly faster than the first half. In general, marathon runners should aim to spend 51% of their time on the first half of the race.

### How are gradually changing pace splits calculated?

If you choose a gradually changing pace, the race splits calculator assumes your pace gradually increases (for negative splits) or gradually reduces (for positive splits) over the race.

The calculation works by fitting a quadratic curve:

*percent of time = (2-4*ø)*(percent of distance)^2 + ((4*ø)
- 1)*percent of distance)
*where ø is the percent of the distance
to be covered at half way.

### How are the two even paced halves splits calculated?

If you choose even-paced halves, the race splits calculator calculates two speeds, on the assumption that you will speed up (for negative splits) or slow down (for positive splits) at exactly half way.

## See also