Split Times Calculator
Plans each split of a race from a target time, either evenly or with a faster second half.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
first half pace = average pace + difference ÷ 2 second half pace = average pace − difference ÷ 2
The two halves cover the same distance, so moving the same amount of pace from one to the other keeps the finish time unchanged.
What to watch out for
A negative split means running the second half faster than the first. It is a common plan for longer races because it protects you from an early surge. A small difference is enough: 5 to 10 seconds per km is plenty for most runners.
Where a split straddles halfway, its time blends the two paces.
Frequently Asked Questions
What is a negative split for a 50-minute 10K?
With 1 km splits and a 10-second difference, 25:25 then 24:35: 5:05 per km, then 4:55 per km.
Are even or negative splits better?
Even or slightly negative pacing suits most races. The bigger risk is running the first half too fast, which costs more later than it gained.