Donaldson R F Speed Converter
Convert a speed between km/h, mph, m/s, knots and Mach — enter it in any one unit to see all the others.
How it is worked out
Every unit converts through metres per second: 1 km/h = 1,000 ÷ 3,600 m/s; 1 mph = 1,609.344 ÷ 3,600 m/s (the international mile is exactly 1,609.344 m); 1 knot = 1,852 ÷ 3,600 m/s (the international nautical mile is exactly 1,852 m); 1 Mach is taken here as 343 m/s, the speed of sound in dry air at 20°C at sea level — the true value changes with air temperature and altitude, so Mach figures here are an approximation, not an aviation-grade one.
Source: SI/international definitions of the mile and nautical mile; speed of sound at 20°C, a standard approximation (e.g. NASA/ISA-style reference conditions).
Looking for pressure units instead? Try the Pressure Converter.