How do I run a negative split?

Run the second half of the distance slightly faster than the first. The split table above assumes an even pace; a negative split means crossing the late markers a little ahead of the times shown, and it is the most reliable way to finish strong rather than fading.

Why is my GPS pace faster than the course markers?

Because a GPS watch over-reads distance. It joins position samples with straight lines and picks up every weave, so it records one to two percent more distance than a course measured to the shortest legal line. More recorded distance for the same time reads as a faster pace than you actually held.

What pace do I need for a target finish time?

Enter your target time and the race distance, and the pace per kilometre and per mile is the pace to hold. The split table then gives the clock time you should see at each marker if you are on track.

Is treadmill pace the same as road pace?

Not quite. A treadmill belt sets the speed, so it is exact, but it removes wind resistance and the small elevation changes of a road, which makes the same pace feel easier. Many runners set a treadmill to a slight incline, around one percent, to bring the effort closer to running outdoors.

Health

Pace Calculator

Enter a distance and a time. The pace, the speed, and the time to reach each split come out exact to the second.

The link carries your figures, so it reopens on exactly these numbers.

Split table

The clock time to reach each marker at this pace, held even. Run the second half a touch faster than the first — a negative split — and you finish ahead of these.

Elapsed time at each split marker.
Marker	Split	Elapsed time
1 km	5:00	5:00
2 km	5:00	10:00
3 km	5:00	15:00
4 km	5:00	20:00
5 km	5:00	25:00
6 km	5:00	30:00
7 km	5:00	35:00
8 km	5:00	40:00
9 km	5:00	45:00
10 km	5:00	50:00

The formula

pace per km = total seconds ÷ distance in km

pace per mile = total seconds ÷ distance in miles

speed = distance ÷ time

split at marker k = pace × k

Worked example

10 km in 50 minutes

50 min = 3000 seconds; 3000 ÷ 10 = 300 s/km
300 s = 5:00 per km
300 × 1.609344 = 8:03 per mile
speed = 10 ÷ (3000 ÷ 3600) = 12.0 km/h

Where this goes wrong

Trusting a GPS pace on a measured course

A GPS watch joins position samples with straight lines, and every weave adds distance a certified course does not have — typically one to two percent. That makes the pace on your wrist a little faster than the one you are truly holding, because a race course is measured to the shortest legal line. The watch says you ran more than 42.2 km; your average pace flatters you. Trust the course markers over the watch.

Questions

How do I run a negative split?: Run the second half of the distance slightly faster than the first. The split table above assumes an even pace; a negative split means crossing the late markers a little ahead of the times shown, and it is the most reliable way to finish strong rather than fading.
Why is my GPS pace faster than the course markers?: Because a GPS watch over-reads distance. It joins position samples with straight lines and picks up every weave, so it records one to two percent more distance than a course measured to the shortest legal line. More recorded distance for the same time reads as a faster pace than you actually held.
What pace do I need for a target finish time?: Enter your target time and the race distance, and the pace per kilometre and per mile is the pace to hold. The split table then gives the clock time you should see at each marker if you are on track.
Is treadmill pace the same as road pace?: Not quite. A treadmill belt sets the speed, so it is exact, but it removes wind resistance and the small elevation changes of a road, which makes the same pace feel easier. Many runners set a treadmill to a slight incline, around one percent, to bring the effort closer to running outdoors.