Three race strategies
With an even split you run every kilometre at the same pace. With a negative split you run the second half faster than the first, 2 percent faster by default. With a positive split it is the other way round: the first half is faster, the second slower. The percentage for negative and positive splits can be adjusted in the calculator.
Many experienced marathoners plan a slight negative split on purpose, because starting too fast costs energy that is missing at the end. A strictly even split is the simplest strategy to pace against.
How the maths works
For an even split, pace is the same throughout: target time divided by distance. For negative and positive splits, the calculator divides the course into two halves and distributes the target time across two paces so that the second half is faster or slower than the first by the chosen percentage. Segment times are rounded to whole seconds, and every rounding carries forward into the cumulative time so the last segment lands exactly on the entered target time. The sum of all segments therefore always matches the target time exactly, not approximately.
Interval and pace band
You choose how often split times appear: every kilometre, every 5 kilometres or every mile. For a marathon or half marathon with many kilometre markers, a 5 km table is often easier to follow mentally, while a 1 km interval is more precise with a pace watch on your wrist.
The button prints the table as a simple pace band for your sleeve or pocket. For converting pace into speed or target time without segments, use the pace calculator; for predicting a realistic target time, use the race time predictor.
Example
For a marathon with a 4:00:00 target and a 2 percent negative split, the first half pace is 5:45 min/km and the second half 5:38 min/km. At the half marathon marker of 21.0975 km the cumulative time is 2:01:13, and the finish lands exactly on 4:00:00.
Frequently asked questions
Why don't my manual segment times add up exactly to the target time?
Rounding to whole seconds can introduce small gaps. The calculator avoids this by building each segment from the difference between two cumulative times rather than an isolated pace, so the sum lands exactly on the target time.
How big should a negative split be?
The default of 2 percent is a cautious guide for a slightly faster second half. What is realistic depends on your fitness and pacing practice, not a fixed rule.
Which interval suits a marathon?
A 5 km interval is enough for rough orientation at aid stations, a 1 km interval matches a GPS watch that beeps at every kilometre anyway.
Can I print the pace band?
Yes, the button under the table opens your browser's print dialog with the current table.
What happens with a custom distance?
A custom distance is treated the same as the fixed distances, just without the half marathon marker. Interval and strategy work the same way.