Race Pace Calculator for Marathon, Half, 10K & 5K (Even or Negative Split)

Negative Split Race Day Pace Calculator

How it works and frequently asked questions

What this tool does

Use this as a race pace calculator and race split calculator for any distance: it works as a marathon pace calculator, half marathon pace calculator, and for 5K and 10K pacing too. Enter your goal time and get mile-by-mile or km-by-km splits, a pace chart, and first-half vs second-half times.

The tool builds a full pacing plan so you can run the second half faster than the first (a negative split). You choose distance (5K, 10K, half, marathon), goal time, and strategy—flat even pace or a negative split (normal or more aggressive). It then gives you a pace chart and structured splits for your race.

It's built for runners who want a clear marathon pacing strategy or half marathon pace strategy—and sensible 5K and 10K pacing—that starts controlled and speeds up later instead of going out too fast and fading.

How to use it

Choose units (miles or kilometres), your distance, and your goal time (hours, minutes, seconds). Pick a race strategy: flat (even pace), normal negative split (recommended), or more aggressive negative split. Click Calculate pace to see your splits, first-half and second-half times and paces, and a downloadable pace chart and PDF.

Even pace vs negative split

With even pace you hold the same speed throughout. With a negative split you run the first half slightly slower and the second half faster, which reduces the risk of blowing up late. You conserve energy early, lock into goal pace in the middle, and push when you're warmed up. This calculator lets you pick either approach and gives you a pace chart and race splits for it.

Frequently asked questions