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.
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Speed of Sound Guide
What do I need to know about 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.
What should I know about 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 compared to 1,235 km/h at sea level, meaning a fixed indicated airspeed corresponds to a higher Mach number at altitude than at ground level.
What do I need to know about 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
What should I know about 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 listener on the ground, which is why a sonic boom is heard as a single event even though the aircraft has been supersonic for some time beforehand.