Calculators / Atmosphere & Weather / Speed of Sound

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Atmosphere & Weather

Speed of Sound Calculator

Estimate the local speed of sound from outside air temperature and compare the result with a Mach 0.80 reference.

Temperature

°C

Speed of sound—

Mach 0.80—

Meters/second—

Sound speed at 15°C

At 15°C (288.15 K), √(1.4 × 287.05287 × 288.15) gives about 340.3 m/s, or 661.5 kt. Mach 0.8 at this temperature is about 529.2 kt.

Temperature must be converted to Kelvin inside the gas-law model. The displayed Mach 0.8 reference is an example, not an aircraft speed limit.

Local speed of sound is calculated from absolute temperature using the ideal-gas relationship for air.