1 knot = 1 nautical mile per hour = 1.852 km/h exactly. Used in aviation, maritime, and meteorology.

Speed relative to the speed of sound. Mach 1 at sea level (15°C) ≈ 340 m/s or 761 mph. Mach varies with temperature and altitude.

How exact are the conversions?

Exact SI: 1 mph = 0.44704 m/s, 1 km/h = 1/3.6 m/s, 1 knot = 0.514444 m/s. Mach uses 343 m/s (sea level, 20°C) as approximation.

Why does Mach change with altitude?

Speed of sound depends on air temperature. At 30,000 feet (-50°C), Mach 1 ≈ 295 m/s vs 343 at sea level. The tool uses sea level reference.

No — all conversions happen in your browser.

Convert between m/s, km/h, mph, knots, ft/s, and Mach.

100% private — no uploads Unit & Data ConvertersFree & unlimited Read tutorial

Watch a quick simulation of this tool in action — no file needed.

Follow these steps — everything happens instantly in your browser.

Everything you might want to know about speed converter.

Length, weight, temperature, area, volume & speed — all in one.

Convert length across mm, cm, m, km, in, ft, yd, mi, nmi, light-years.

Convert between MPG (US/UK), L/100km, and km/L.

Convert between Hz, kHz, MHz, GHz, RPM, and angular units.