Even
Same pace, every split
Negative
Second half faster
Positive
First half faster
Even splits
Even pacing targets the same pace for every kilometer or mile of the race. It's the simplest strategy to plan and the easiest to follow on race day, since every split has the same target. The tradeoff: it doesn't account for fatigue in the second half or for hills on the course, so it works best on flat, fast courses like Berlin or Chicago, run at a controlled effort.
If you have a time goal in mind, start from its pace: sub-3:00, sub-3:30, sub-4:00, sub-4:30, or sub-5:00.
Negative splits
A negative split plan runs the second half of the race faster than the first. Most elite marathoners race this way on purpose: starting conservatively keeps glycogen and legs in reserve for the back half, when fatigue and any late climbs hit hardest. It's the highest-upside strategy for a personal best, but it takes discipline early — the first few kilometers should feel almost too easy.
Positive splits
A positive split plan runs the first half faster than the second. This isn't usually a goal — it's what happens when a race starts too fast and fatigue takes over late. The one place it's a deliberate choice is a course that front-loads its climbs (net downhill courses, or courses with early hills and a flat or downhill finish), where banking a little time early can offset a harder middle section.
Adjusting pace for hills
None of these strategies account for elevation on their own — they assume a flat course. Real marathon courses climb and descend, and effort, not pace, is what should stay steady. That means slowing target pace slightly on climbs and allowing it to drop on descents, so the overall effort — and the total time against your goal — stays on track. This is the difference between a flat pace band and an elevation-adjusted plan.
Rule of thumb: a steady 3% climb costs roughly 15–20 seconds per kilometre at marathon effort. The calculator does this math per split, from the course's real profile.
Building your plan
Marathon Splits builds a kilometer-by-kilometer or mile-by-mile split plan for any of these three strategies, adjusted for a course's real elevation profile when GPX data is available. Enter a goal finish time, pick even, negative, or positive splits, and choose a supported course or upload your own GPX file.
Build a split plan or start from a specific course: