AudioCalcs
Speed of Sound Calculator — Temperature & Humidity Correction
Calculate the speed of sound in air at different temperatures and humidity levels.
How We Calculate This
Speed of sound (dry air) = 331.3 + 0.606 × T
where T is the temperature in degrees Celsius.
The humidity correction is small and approximate — humid air is slightly less dense than dry air, increasing the speed by about 0.4% at 20°C and 100% relative humidity (≈+1.4 m/s), rising to roughly 0.6% at warmer temperatures. At and below 0°C the correction is held at zero, because freezing air holds very little water vapour. The exact effect depends non-linearly on the saturation vapour pressure, so treat this as an indicative first-order estimate.
For audio delay calculations, the time per metre is: 1000 / speed (m/s) = ms per metre
Frequently Asked Questions
At 20°C (68°F) in dry air, sound travels at approximately 343.2 m/s (1,235 km/h or 767 mph). This is often rounded to 343 m/s for quick calculations.
Yes, but only slightly. Humid air is less dense than dry air (water vapour is lighter than nitrogen and oxygen), so sound travels slightly faster in humid conditions — typically about 0.1-0.6% faster depending on temperature and humidity.
Speaker delay alignment uses the speed of sound to calculate time offsets. At 343 m/s, sound takes approximately 2.92 ms per metre. A delay speaker 10 m behind the main PA would need about 29 ms of delay to stay in sync.
Altitude itself does not directly affect the speed of sound in an ideal gas. However, temperature decreases with altitude (roughly 6.5°C per 1000 m), which does slow sound down. At higher altitudes the lower temperature is the main factor.
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Last updated: February 2026
All calculations are estimates based on standard formulas. Always verify results for critical applications.