Pace Calculator

When to use this

You have signed up for a half marathon and your goal is to finish under two hours. What pace per mile do you need to hold? Or you ran 5 kilometers in 27 minutes on your last training run and want to know your per-mile and per-kilometer splits. This calculator solves the three-variable relationship between pace, distance, and time — give it any two, and it returns the third.

Runners use pace calculators constantly during training blocks. You might need to figure out your target pace for a tempo run (typically 25–30 seconds per mile faster than race pace), your easy-day pace (usually 1–2 minutes per mile slower than race pace), or what finish time you can expect if you hold your current training pace over the full race distance. Race presets for 5K, 10K, half marathon, and marathon eliminate the need to remember exact distances.

The splits table is particularly useful for race-day planning. Rather than just knowing your average pace, you can see your expected time at each mile marker. Many runners tape their splits to their wrist or enter them into a GPS watch. Going out too fast in the first miles is the most common race-day mistake, and having concrete split targets helps you stay disciplined.

Good to know

Even pacing is almost always the fastest strategy. Running the first half of a race at the same pace as the second half — or slightly slower — produces better finish times than starting fast and fading. The exception is downhill courses or races with significant wind changes, where terrain may dictate pace adjustments.

Pace per mile and pace per kilometer feel different than you expect. An 8:00/mile pace equals roughly 4:58/km. If you train with one unit and race with the other, make sure you convert in advance so you are not confused by mile-marker clocks or GPS readings on race day.

Temperature affects pace more than most runners realize. For every 10°F above 55°F, expect your pace to slow by about 1.5–3% — a pace that feels easy at 50°F becomes noticeably harder at 80°F. Adjust your target pace on hot days rather than pushing through and risking a blow-up in the later miles.

The relationship between 5K and marathon pace. As a rough rule, your marathon pace is typically 15–20% slower than your 5K pace. If you can run a 24-minute 5K (7:44/mi), a realistic marathon target is around 9:00–9:15/mi, or about a 3:56–4:02 finish.

Quick Reference

Race	Distance	Common Goal Times	Pace Required
5K	3.1 mi	25:00	8:03/mi
5K	3.1 mi	30:00	9:40/mi
10K	6.2 mi	50:00	8:03/mi
10K	6.2 mi	60:00	9:40/mi
Half Marathon	13.1 mi	1:45:00	8:01/mi
Half Marathon	13.1 mi	2:00:00	9:09/mi
Marathon	26.2 mi	3:30:00	8:01/mi
Marathon	26.2 mi	4:00:00	9:09/mi
Marathon	26.2 mi	4:30:00	10:18/mi