Split calculator
Enter a distance and a goal time to get the split for every kilometre or mile, evenly paced or with a faster second half.
How the calculation works
Your average pace is the goal time divided by the distance. With an even split every kilometre or mile is run at that pace.
For a negative split the calculator lowers the pace of the second half and raises the pace of the first by the same amount, so the two halves differ by the percentage you choose and the total time stays exactly your goal time. A split that crosses the halfway point mixes the two paces in proportion to how much of it lies on each side.
first half = pace × (1 + d ÷ 2)
second half = pace × (1 − d ÷ 2)
- pace
- your average pace (goal time ÷ distance)
- d
- how much faster the second half is, as a fraction of the average pace (0.02 = 2%)
Example: a 50-minute 10K
The average pace is 5:00 per kilometre. With a 2% negative split the first 5 km are run at 5:03 per kilometre (25:15) and the last 5 km at 4:57 per kilometre (24:45). The total is still 50:00.
Choosing a pacing strategy
An even pace is the safest plan on a flat course. A small negative split of 1 to 3% is realistic for experienced runners and protects against starting too fast. On a hilly course, or in heat or wind, an even effort matters more than an even pace, so treat the splits as a guide and adjust on the day.
Examples
Frequently asked questions
What is a negative split?
Running the second half of a race faster than the first. The total time is the same as an even pace, but you start more conservatively and finish stronger.
Is a negative split better than an even pace?
For most runners a small negative split or an even pace works best, because going out too fast is the most common cause of a slow second half. Large differences are hard to run and are not needed to reach a goal time.
Why is the last split shorter?
A race distance is rarely a whole number of kilometres or miles. A marathon is 42.195 km, so the last split covers 195 metres. The calculator shows it as its own row.
How do I print a pace band?
Calculate your splits and use Print pace band. Only the title, the result and the splits table are printed, so you can fold it into a wristband or tape it to a bottle.
Related calculators
Sources
- World Athletics, Technical Rules – standard road race distances (the marathon is 42.195 km, the half marathon 21.0975 km)
- International mile = 1.609344 km, by definition (NIST, Guide for the Use of the International System of Units)