Convert Knot (UK) (kt (UK)) to Mach (20°C, 1 atm) (Ma (20°C)) instantly.
About these units
Knot (UK) (kt (UK))
The UK knot historically varied slightly from the international knot because the UK used different values for the nautical mile depending on era and maritime authority. Though the differences were minor, they mattered in navigation, where precision affects charting, dead reckoning, and ocean voyaging. Modern UK practice fully aligns with the international knot (1 nautical mile per hour), but historical documents and charts may reference older UK knot values. The knot's rich maritime heritage—used by sailors measuring speed with knotted ropes dragged along the water—makes it one of the oldest continuously used speed units.
Mach (20°C, 1 atm) (Ma (20°C))
At 20°C and 1 atmosphere, the speed of sound in air is about 343 m/s, making Mach 1 = 343 m/s under those conditions. Mach numbers classify aerodynamic regimes: Mach 0.3–0.8 (Subsonic), Mach 0.8–1.2 (Transonic), Mach 1–5 (Supersonic), Mach 5+ (Hypersonic). Temperature influences Mach speed significantly; colder air slows sound, while warmer air increases its speed. Aircraft design, jet engines, wind tunnels, aerospace testing, and atmospheric re-entry physics all rely heavily on Mach numbers referenced to standard conditions.