How fast does sound travel at room temperature?

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.

Does humidity affect the speed of sound?

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.

Why does the speed of sound matter for live sound?

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.

How does altitude affect the speed of sound?

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.

AudioCalcs

Speed of Sound Calculator — Temperature & Humidity Correction

Calculate the speed of sound in air at different temperatures and humidity levels.

Temperature

Relative Humidity

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 — humid air is slightly less dense than dry air, increasing the speed by up to about 0.6% at high temperatures and 100% humidity.

For audio delay calculations, the time per metre is: 1000 / speed (m/s) = ms per metre

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.