How do I convert pace (min/km) to speed (km/h)?

Divide 3,600 (seconds in an hour) by your pace in seconds per km. A 5:00/km pace is 300 seconds per km, so 3,600 ÷ 300 = 12 km/h.

How do I convert speed (km/h) back to pace?

Divide 3,600 by your speed in km/h to get seconds per km. At 12 km/h: 3,600 ÷ 12 = 300 seconds per km = 5:00/km.

Why does my treadmill show speed but my running watch shows pace?

Treadmills set a fixed belt speed, so km/h (or mph) is the natural control unit. Running watches track how long it takes to cover a fixed distance from GPS, so pace (time per distance) is the more direct output. Both describe the same physical rate — they're just measured from opposite ends of the same ratio.

Is a faster pace a bigger or smaller number?

Smaller. Pace is time per distance, so less time to cover the same distance means a faster pace and a lower number (4:00/km is faster than 5:00/km). Speed works the other way — a bigger km/h number means faster. This inverse relationship is the most common source of pace-vs-speed mix-ups.

Guide

Pace to speed: converting min/km to km/h (and back)

Pace and speed measure the same effort from opposite directions — one's a rate of time, the other a rate of distance.

By Buğra SözeriPublished September 25, 2026

Pace and speed describe the same thing — how fast you’re moving — but they’re inverses of each other. Pace is time per distance (minutes per km). Speed is distance per time(km per hour). Converting between them isn’t a lookup table; it’s a single division using the number of seconds in an hour.

The formula

Speed (km/h) = 3,600 ÷ pace (seconds per km). And the reverse: pace (seconds per km) = 3,600 ÷ speed (km/h). The 3,600 comes from the number of seconds in an hour — it’s what makes the two rates directly invertible without needing to know the distance run.

Pace (min/km)	Speed (km/h)
4:00 /km	15.0 km/h
5:00 /km	12.0 km/h
6:00 /km	10.0 km/h
7:00 /km	8.6 km/h
8:00 /km	7.5 km/h

Worked example for the 5:00/km row: 5 minutes = 300 seconds. 3,600 ÷ 300 = 12 km/h. Going the other way, a treadmill set to 10 km/h converts to 3,600 ÷ 10 = 360 seconds per km, which is 6:00/km pace.

Why the two units exist for the same activity

Treadmills are built around a fixed belt speed — you set km/h or mph and the belt moves at that constant rate, so speed is the natural control input. GPS running watches work the opposite way: they measure distance covered over a fixed time interval and report the result as pace, because “how long per km” is what most runners plan workouts and race splits around. Neither unit is more “correct” — they’re just optimized for different tools.

This is also why race-pace planning (see marathon pace calculator by finish time) uses pace, while treadmill interval workouts are usually programmed in speed — you’re describing the same effort with the unit that matches how the device is controlled.

Common mix-up: bigger number, faster or slower?

Because pace and speed are inverses, a bigger number means the opposite thing in each system. Going from 5:00/km to 4:00/km pace is faster (smaller pace number, less time per km) — the equivalent speed goes from 12 km/h up to 15 km/h (bigger speed number, faster). If you're converting a treadmill workout to pace for outdoor training, double-check which direction the numbers should move, since getting it backward silently produces a much easier or much harder session than intended. For distance-unit conversions on top of pace/speed, see the speed converters.

Frequently asked questions

How do I convert pace (min/km) to speed (km/h)?: Divide 3,600 (seconds in an hour) by your pace in seconds per km. A 5:00/km pace is 300 seconds per km, so 3,600 ÷ 300 = 12 km/h.
How do I convert speed (km/h) back to pace?: Divide 3,600 by your speed in km/h to get seconds per km. At 12 km/h: 3,600 ÷ 12 = 300 seconds per km = 5:00/km.
Why does my treadmill show speed but my running watch shows pace?: Treadmills set a fixed belt speed, so km/h (or mph) is the natural control unit. Running watches track how long it takes to cover a fixed distance from GPS, so pace (time per distance) is the more direct output. Both describe the same physical rate — they're just measured from opposite ends of the same ratio.
Is a faster pace a bigger or smaller number?: Smaller. Pace is time per distance, so less time to cover the same distance means a faster pace and a lower number (4:00/km is faster than 5:00/km). Speed works the other way — a bigger km/h number means faster. This inverse relationship is the most common source of pace-vs-speed mix-ups.

Sources & references

Authoritative references cited by this piece. Verified by Buğra Sözeri on the dates shown and re-checked at every deploy.

NIST SP 811 — Guide for the Use of the International System of Units — Reference for SI-consistent handling of rate units like km/h derived from a time-per-distance pace(as of 2026-09-25)
BIPM — SI Brochure, derived unit for velocity (m/s) — The SI derived-unit basis (distance/time) that both pace and speed ultimately express(as of 2026-09-25)