Mach Number & Speed of Sound Calculator
Compute the speed of sound in air at a given temperature and the Mach number of an object moving through it — the ratio of its speed to the local speed of sound. Also gives the Mach angle of the shock wave (for supersonic flight) and classifies the regime (subsonic, transonic, supersonic, hypersonic). Handy for aviation, acoustics, and aerodynamics back-of-envelope work. Runs locally in your browser.
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The speed of sound in air is c = 331.3 · √(1 + T/273.15) m/s with T in Celsius — about 331.3 m/s at 0 °C and 343.2 m/s at 20 °C. The Mach number is M = v / c (dimensionless). The Mach angle μ satisfies sin μ = 1 / M and is defined only for M ≥ 1 (the shock cone half-angle; μ = 90° exactly at Mach 1, narrowing toward 0° at higher Mach). Regime classification: M < 0.8 subsonic, 0.8–1.2 transonic, 1.2–5 supersonic, ≥ 5 hypersonic. Speed units convert: 1 m/s = 3.6 km/h = 2.23694 mph = 1.94384 knot. The model assumes dry air and is a good approximation for the troposphere; humidity and composition shift c by a small amount. Pairs with the Wavelength/Frequency and Decibel tools. Everything runs locally — nothing leaves your browser.