4:21
/km · 13.79 km/h
4:21 per km — marathon in 3:03:33, 13.79 km/h
Running 4:21 per kilometre is 13.79 km/h. Hold it and the half comes in at 1:31:46, the marathon at 3:03:33.
Finish times
These assume you hold the pace from gun to tape. Most runners drift slower in the second half, so leave a margin when setting a target.
- 5K
- 21:45
- 10K
- 43:30
- Half
- 1:31:46
- Marathon
- 3:03:33
- Speed
- 13.79 km/h
- Metres per second
- 3.831 m/s
- Pace per mile
- 7:00
- One lap (400 m)
- 1:44
What this pace breaks
The cut-offs are tighter than they look: a sub-4 marathon needs 5:41 per kilometre, and one second slower puts you over four hours.
sub-20 min 5K · nosub-25 min 5K · yessub-30 min 5K · yessub-50 min 10K · yessub-60 min 10K · yessub-100 min Half · yessub-2h Half · yessub-3h Marathon · nosub-3:30h Marathon · yessub-4h Marathon · yessub-5h Marathon · yes
Nearby paces
The half and the full are not round numbers
A marathon is 42.195 km and a half is 21.0975 km. Rounding to 42 km costs you about a minute at a 5:00 pace — small, but enough to miss a target.
How to read this
- Pace is the time for one kilometre, so a smaller number means faster.
- To get speed, divide 3600 by the pace in seconds: 300 s gives 12 km/h.
- A finish time is simply the pace multiplied by the distance.
- Mile pace is kilometre pace times 1.609344.
Frequently asked questions
Q. What marathon time does 4:21 per km give?
3:03:33. The half comes in at 1:31:46, the 10K at 43:30 and the 5K at 21:45.
Q. How fast is 4:21 per km in km/h?
13.79 km/h, or 3.831 metres per second.
Q. What is that per mile?
7:00, because a mile is 1.609344 km.
Q. And one lap of the track?
1:44 for 400 m.