Half Marathon Pacing Split
Calculator

It divides your goal finish time evenly across the 21.1 km (13.1 mile) distance to produce a target pace per split, then lists the cumulative time at each checkpoint. This gives you a pacing chart to follow during the race.

Negative splits, running the second half slightly faster than the first, are generally recommended because starting conservatively conserves glycogen and reduces the risk of a late-race fade. Many experienced half marathoners aim for a slightly slower first 5K before settling into or slightly exceeding goal pace.

Fatigue, glycogen depletion, and accumulated muscular fatigue naturally slow pace in the final miles for most runners, even with good pacing early on. This is normal and part of why slightly front-conservative pacing strategies tend to produce better overall results than a flat, ambitious pace held from the start.

Even, calculated splits assume flat terrain, so on hilly courses it's better to run by effort on climbs and descents rather than rigidly hitting each split, since uphill segments will naturally be slower and downhills faster for the same effort. Use the flat-pace splits as a general framework rather than an exact target on hilly terrain.

A common approach for first-timers is to base goal pace on a recent 10K or 5K time using a race-time prediction formula, then add a small buffer since half marathon endurance demands differ from shorter races. Starting slightly conservative on debut attempts tends to produce a more positive race experience than an overly ambitious target.