Race Pace Split Calculator
Plan your race with a split-by-split pacing strategy from 5K to 100K. Set your goal time, choose your pacing approach, and get a per-km or per-mile breakdown with a pace chart. Print the wristband for race day.
Pace per Split faster at top - - - avg pace
Finish Time Predictor
Based on your current distance and target time, using Riegel's formula (T2 = T1 x (D2/D1)^1.06).
| Distance | Predicted Time | Avg Pace |
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Learn more: even, negative and positive split pacing
The three strategies
Wikipedia's negative split article defines a negative split as completing the second half of a race faster than the first, a positive split as the first half faster than the second, and an even split as running the same split for every lap. It does not declare any strategy best. It notes that Kenenisa Bekele used negative splits in all his world records, with 5000 m kilometers of 2:33, 2:32, 2:31, 2:30 and 2:29.
How the tool builds splits
The tool applies a pace factor to each split that changes in a straight line from the first to the last. For a negative split with a variance of 3%, the first split runs 3% slower than the average and the last 3% faster. For a positive split it is the other way round. It then rescales all the splits so the total time matches your goal exactly.
For a 4:00:00 marathon in kilometres with a 3% variance, the even split is 5:41 per km throughout. The negative split starts at 5:51, passes 5:42 at km 21 and ends at 5:31. The positive split is the reverse, from 5:31 to 5:52. The first half takes 2:01:18 with the negative split and 1:57:36 with the positive one. The last piece of 195 m gets the final pace.
Because the splits are rescaled, the starting pace is not exactly 3% off the average. In the example it is 5:51, a little over 3% slower than 5:41, and the average pace is held.
Choosing a variance
The variance sets how far apart the first and last splits are. A small value such as 1 to 3% gives a gentle change. A bigger one is mainly for trying out a plan on paper. The tool does not decide which strategy is best for you.
The splits come from your target time and strategy only. They do not allow for hills, heat or wind, so adjust the plan for those yourself.
FAQ
What is a negative split?
Running the second half of a race faster than the first, by Wikipedia's definition. The tool builds one by starting slower than average and finishing faster, in even steps.
What variance should I use?
The tool accepts any value. Small figures such as 1 to 3% give a gradual change, and larger ones give a steeper plan. Try a few and look at the first and last pace.
Does it account for terrain or weather?
No. Splits come from the target time and the strategy alone. Adjust for hills, heat and wind yourself.