Pace vs. Speed — What's the Difference?
Pace measures time per unit of distance (minutes per km or mile), while speed measures distance per unit of time (km/h or mph). Runners typically think in pace since race splits and training plans are usually structured around minutes-per-mile or minutes-per-km targets, while cyclists more often think in speed.
Common Race Distances
5K (3.1 miles), 10K (6.2 miles), half marathon (13.1 miles / 21.1 km), and marathon (26.2 miles / 42.2 km) are the standard road race distances worldwide, and pace calculators are most often used to plan a target pace for one of these based on a goal finish time.
How to Use a Pace Calculator for Race Training
A common approach is to calculate the pace needed for a goal finish time first, then use that pace during training runs to build familiarity with how that effort level feels. Many runners find that a pace which feels sustainable in a short training run feels considerably harder to hold across a full race distance, since fatigue accumulates non-linearly over longer efforts.
Negative Splits vs. Even Pacing
Even pacing means running each segment at roughly the same pace throughout. A "negative split" strategy — running the second half slightly faster than the first — is associated with better race outcomes in distance running, since starting conservatively helps avoid the glycogen depletion and pace collapse that often comes from starting too fast.
Converting Between Pace and Speed
Pace and speed are mathematically inverse — a 6:00 min/km pace equals exactly 10 km/h, and a 5:00 min/mile pace equals exactly 12 mph. This calculator converts automatically between km and miles so the same effort can be compared regardless of which unit a race or training plan uses.