Speed, Distance & Time
Solve d = v·t for speed, distance or time with km, miles, metres, nautical miles, km/h, mph, m/s, knots and running pace — time as h:mm:ss or decimal hours.
The missing quantity, plus the distance in every unit, the speed in every unit including min/km and min/mile pace, and the time as h:mm:ss and decimal hours.
Example: 10 km at 12 km/h → 0:50:00 (pace 5:00 min/km, 7.46 mph, 6.48 knots). A marathon (42.195 km) in 3:30:00 → 12.06 km/h, 4:59 min/km. 20 knots for 2 h 30 m → 50 nautical miles.
One formula,
every unit.
How the three quantities relate, how the units convert, and how the time is read.
d = v × t
Distance equals speed times time; the page solves for whichever you leave out. Every input converts to metres and seconds first, so a marathon in km with a time in h:mm:ss and a speed wanted in knots is one calculation. Exact factors: 1 mile = 1 609.344 m, 1 nautical mile = 1 852 m, 1 knot = 1 nautical mile per hour.
Pace
Runners think in minutes per kilometre or per mile — the inverse of speed. 12 km/h is 5:00 min/km; entering a pace as the speed works the same way. Both paces are always shown.
Reading the time
h:mm:ss, mm:ss written as 0:mm:ss, "1h 30m 20s", or a decimal number of hours all work. A bare "1:30" is read as one hour thirty minutes and the page says so. The result is an average over the whole distance — stops and hills are inside it. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- d = v × t through SI; exact factors 1 mi = 1 609.344 m, 1 nmi = 1 852 m, 1 knot = 1 nmi/h; pace = time per unit distance
Last reviewed 21 September 2026. How results are checked: How we verify.