Cyclists talk in miles per hour. Runners talk in minutes per mile. Same underlying physics — distance over time — but the convention flips, and it isn't just habit. Pace and speed answer different questions, and racing rewards the one runners actually use.
Why pace wins for runners
Speed answers "how fast." Pace answers "how long will this take me" — which is the question that actually matters when you're staring at mile markers and doing math on tired legs. A goal of "8:00 per mile" tells you directly what the clock should read at every mile marker. A goal of "7.5 mph" requires converting on the fly, mid-race, which is exactly when mental arithmetic gets unreliable.
The conversion itself is simple — pace (minutes per mile) = 60 / speed (mph) — but simple isn't the same as fast when you're 18 miles into a marathon. Runners standardized on pace because it removes a conversion step at the exact moment focus is scarcest.
The math, when you need it
Worked example: A treadmill set to 7.5 mph is running 8:00 per mile (60 ÷ 7.5 = 8). Bump the treadmill to 8.0 mph and pace drops to 7:30 per mile (60 ÷ 8 = 7.5 minutes). Small speed changes compress into noticeably different paces at the low end of the scale — the jump from 5 mph to 6 mph (12:00 to 10:00 pace) is a bigger per-mile swing than 9 mph to 10 mph (6:40 to 6:00), even though both are "1 mph faster."
Run the numbers either direction in the Pace Unit Converter or the Speed ↔ Pace calculator — useful any time a treadmill display, a GPS watch's default readout, or a race director's course notes hand you the wrong unit for the math you're actually trying to do.
Where speed still matters
Speed isn't useless — it's the natural unit for treadmill dials and for comparing effort across very different distances and species of workout (mile repeats versus tempo miles versus an easy shuffle). But for the one number that matters on race day — will I hit my goal time — pace is the more direct tool, which is why every split table on this site, and on your watch, is built around it.