Speed Converter

Speed conversion translates a value between the metric system (m/s, km/h), the mile-based mph, the knot used in aviation/navigation, and mach based on the speed of sound. This tool converts every unit through a common meters per second (m/s) base so any pair can be computed instantly.

Enter a value, choose the from and to units, and the result updates automatically. Use Swap units to flip the two selections.

Result = value × (from-unit m/s) ÷ (to-unit m/s)

Common conversions: 100 km/h ≈ 27.8 m/s, 1 knot ≈ 1.852 km/h, Mach 1 ≈ 340.29 m/s (~1225 km/h).

A knot is the speed of covering 1 nautical mile (1,852m) in one hour. A nautical mile is defined as the distance spanned by 1 minute of latitude (1/60 of a degree), which lets a chart's latitude scale double as a distance ruler. Even in the GPS era, aircraft and ships still standardize on knots because it lets flight and route planning use the same latitude/longitude grid for both position and speed/distance math. Land-based units like km/h or mph work fine for road signs but don't connect directly to a map's lat/long grid.

Marathon and running culture, meanwhile, expresses speed as pace (min/km, the time to cover 1km) instead. A shorter pace (e.g. 4 min/km) means a faster speed (15 km/h), while a longer pace (e.g. 7 min/km) means a slower one (8.57 km/h). Runners prefer pace over instantaneous speed because it's easier to back-calculate a target finish time from distance. For example, running a full marathon (42.195km) at a 5 min/km pace takes about 3 hours 31 minutes (210.975 minutes) in total.