Speed of Sound Calculator
Calculate the speed of sound in air at any temperature, or in water and other media. Convert speeds to Mach numbers and find sonic boom distances.
Speed of Sound Guide
Temperature and the Speed of Sound
The speed of sound in air depends primarily on temperature: v = 331.3 × √(1 + T/273.15) m/s, where T is temperature in Celsius. At 0°C: 331 m/s. At 20°C: 343 m/s. At 100°C: 386 m/s. The relationship is not linear — it scales with the square root of absolute temperature. Humidity has a very small effect on speed of sound (less than 0.5% at typical conditions). Pressure changes (altitude) do not significantly affect the speed of sound at a given temperature — despite common misconception.
Mach Numbers
The Mach number is the ratio of an object's speed to the local speed of sound. Mach 1 = the speed of sound (approximately 343 m/s or 1,235 km/h at sea level and 20°C). Subsonic: below Mach 0.8. Transonic: Mach 0.8–1.2 (where shock waves begin to form). Supersonic: Mach 1–5. Hypersonic: Mach 5+. The speed of sound decreases with altitude as temperature falls — at 35,000 feet (typical cruise altitude), the speed of sound is approximately 295 m/s (Mach 1 at cruise = 1,062 km/h vs 1,235 km/h at sea
Sound in Different Media
Sound travels faster in denser, stiffer materials: air at 20°C (343 m/s) < water (1,481 m/s) < wood (3,500–4,200 m/s) < glass (5,640 m/s) < steel (5,960 m/s) < diamond (12,000 m/s). This is why knocking on a wall to detect a stud works — the denser wood produces a different acoustic response than the hollow cavity. Dolphins and whales exploit the higher speed of sound in water for long-distance communication — whale song can travel thousands of miles through ocean 'sound channels' where the spee
Thunder and Sonic Booms
Lightning produces a thunder clap at the strike location. The time between seeing lightning and hearing thunder tells you the distance: approximately 1km per 3 seconds (or 1 mile per 5 seconds). This works because light travels almost instantaneously at 300,000 km/s while sound travels at only 0.343 km/s. A sonic boom occurs when an aircraft or projectile exceeds the speed of sound — the shock wave produced is a cone trailing behind the object. The 'boom' is heard when this cone sweeps past a li
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