How pace and speed are calculated
Pace is how long it takes to cover one kilometer; speed is how far you cover in one hour. Both come from the same total time and distance.
- distance — distance covered, in km
- time — hr + min + sec, converted to total minutes
More detail
Pace vs. speed
Pace and speed describe the same effort two ways: pace (min/km) is what runners use to judge splits, speed (km/h) is easier to compare against treadmill settings. A 5:00/km pace is exactly 12.0 km/h.
Common race distances
5K, 10K, half marathon (21.0975 km), and marathon (42.195 km) are the standard distances — plug in your finish time for any of them to see the pace you'd need to hold.
Practical tip. Negative splits (running the second half slightly faster than the first) tend to feel better and produce more consistent finish times than starting too fast.
Frequently asked questions
What pace do I need for a sub-4-hour marathon?
You'd need to average 5:41/km (about 9:09/mile) across 42.195 km. Enter 42.195 as the distance and 3:59:59 as the time above to see the exact pace and speed.
How do I convert pace per km to pace per mile?
Multiply your min/km pace by 1.60934 (km per mile). Enter your distance and time above and both are calculated automatically — a 5:00/km pace works out to about 8:03/mile.
What's a good goal pace for a half marathon?
It depends entirely on your fitness and training — there's no universal target. Enter 21.0975 km with a goal finish time above to see the exact pace you'd need to hold for that distance.
Why does my GPS watch show a different pace than a race result?
GPS distance tracking typically has a small margin of error (often 1-2% over a long run) from signal drift and route deviation, while certified race courses are precisely measured — small gaps between the two are normal.