Marathon Split Planner

Pick a goal time and a pacing strategy. We’ll lay out every 5K split you need to hit, plus the cumulative time at each marker.

Format: h:mm:ss (e.g. 3:30:00).
How much faster (or slower) the second half is than the first.

Splits assume two-tier pacing: a steady first half, then a faster (or slower) second half. Most successful marathoners run an even or slightly negative split — positive splits usually come from going out too hot. Adjust for terrain on hilly courses.

How this is calculated

Average pace is your goal time divided by 42.195 km. For an even split, every 5K segment runs at exactly that pace, and the final 2.195 km does too.

For a negative or positive split, we shift time between the two halves: a 60-second negative split means the second half finishes one minute faster than the first. Within each half, splits are evenly paced; the 20–25 km split straddles the halfway point and uses both paces proportionally.