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

Temperature in degrees

Relative Humidity

Ambient humidity level

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

Related Calculators

dB Conversion Calculator

Convert between dBu, dBV, dBFS, dBm and voltage or power values instantly. An essential daily reference calculator for audio engineers.

Frequency to Note Calculator

Find the closest musical note to any frequency with cents deviation from equal temperament. Free online audio reference calculator.

Wavelength Calculator

Calculate the wavelength of any sound wave at a given frequency and air temperature. Useful for speaker placement and room acoustics.

Audio Power Calculator

Calculate audio power from voltage and impedance, or find voltage from power and impedance. Essential for amplifier and speaker work.

Voltage Calculator

Calculate audio signal voltage from dBu or dBV decibel values and convert back to dB. Essential reference for gain staging and setup.

Last updated: February 2026

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