A worked example: 5:00 min/km
A pace of 5 minutes per kilometer converts to 8:03 minutes per mile, equivalent to a speed of 12 km/h or 7.46 mph.
The method: pace → speed → pace
3600 seconds divided by the pace in seconds gives the equivalent speed (km/h if the pace was per-km) — 3600 ÷ 300 seconds = 12 km/h for a 5:00/km pace. That speed converts to mph by dividing by the km-per-mile factor (1.609344), and then 3600 divided by the mph speed gives the pace per mile.
A faster pace: 4:30/km
A quicker 4 minutes 30 seconds per km works out to 13.33 km/h (8.28 mph), converting to a 7:15 per-mile pace — a faster per-km pace always corresponds to both a higher speed and a faster per-mile pace, moving in the same direction.
Why lower pace numbers mean faster running
Pace and speed point in opposite directions: a smaller pace number (less time per distance) means a higher speed. This is the opposite of how most numbers work in fitness contexts, where bigger usually means "more" — worth keeping straight when comparing paces.
What "a good pace" actually depends on
Typical recreational runners often run 6-8 min/km, while competitive runners may run under 4 min/km — there's no universal "good" pace, only one appropriate to a specific runner's fitness level and training goal.