Running Pace Calculator

Pace is the fundamental unit of running. Instead of "speed in km/h" as in cycling or motorsports, runners think in "minutes per kilometer" — the lower the number, the faster. This calculator converts any combination of distance and time into pace and speed, and projects your times across the four canonical race distances: 5k, 10k, half marathon (21.0975 km), and marathon (42.195 km).

Formulas:

Pace (min/km) = Total time ÷ Distance
Speed (km/h)  = Distance ÷ (Time in hours)
Time at race X = Pace × Race X distance

Reference paces by level: beginner: 7:00–8:30 min/km. Regular intermediate: 5:30–6:30 min/km. Experienced: 4:30–5:30 min/km. Competitive amateur: 3:50–4:30 min/km. World elite: 2:50–3:00 min/km. To run a sub-4 marathon, you need 5:41 min/km. The legendary sub-3 marathon for amateurs requires 4:16 min/km sustained.

Important caveat: extrapolating short-distance times to long ones has limits. Holding 5k pace for 42k is nearly impossible — fatigue and glycogen depletion change the game. Riegel's rule (T₂ = T₁ × (D₂/D₁)^1.06) is more realistic for long projections: each time you double the distance, time more than doubles. For accurate projections, do tune-up races of 10–15 km and use specialized tools like Jack Daniels' VDOT.