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Speed of Sound in Air Calculator

Calculate the speed of sound in dry air at a given temperature, from the standard adiabatic formula.

Speed of sound
343.21 m/s
In feet per second
1,126 ft/s
In km/h
1,235.6 km/h
In mph
767.7 mph

How it works

The speed of sound in dry air depends on temperature: c = 331.3 × √(1 + T ⁄ 273.15) m/s, where T is the air temperature in Celsius. This comes from treating air as an ideal gas and sound as an adiabatic (no heat exchange) pressure wave; 331.3 m/s is the speed of sound at 0°C, and the square-root term captures how that speed rises as the air warms — molecules colliding faster transmit a pressure disturbance faster.

This is the exact closed-form version of the relationship; you may also see the simpler linear approximation c ≈ 331.3 + 0.606×T, which is only accurate near room temperature. This calculator uses the square-root form so it stays accurate across a wider temperature range, including well below freezing.

The input is Celsius only — converting to Fahrenheit isn't a simple rescaling (it also shifts by an offset), so it doesn't fit this site's single-multiplier metric/imperial toggle used elsewhere. The result is shown in m/s, ft/s, km/h, and mph so it's still useful regardless of which unit system you think in.

FAQ

Why does temperature affect the speed of sound but not humidity or pressure much?

Sound speed in an ideal gas depends on temperature because it changes how fast gas molecules move on average. Air pressure barely matters because pressure and density change together, and their effects on sound speed cancel out. Humidity has a small effect (moist air is very slightly less dense than dry air at the same temperature and pressure, so sound travels marginally faster) — small enough that this calculator, like most standard references, treats air as dry.

Why is the speed of sound different in water or steel?

This formula is specific to air (or more precisely, to an ideal gas with air's properties). Sound travels much faster through liquids and solids — roughly 1,480 m/s in water and around 5,000 m/s in steel — because the formula for speed of sound in those media depends on stiffness and density in a different way than it does for a gas.

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