# Speed of Sound - Online Calculator

The speed of sound in air (or in other gases) can be expressed as

c = (k p / ρ)^{1/2}

= (k R T)^{1/2}(1)

where

c = speed of sound (m/s, ft/s)

k = ratio of specific heats (adiabatic index, isentropic expansion factor)

p = pressure (Pa, psi)

R = 286.9 (J/kg K) = 1,716 (ft lb/slug^{o}R) = individual gas constant specific for air

T = absolute temperature (K, R)

The calculators below can be used to estimate the speed of sound in air at temperatures close to *273.15 K (0 ^{o}C, 32^{o}F)*.

### Speed of Sound - SI Units

### Speed of Sound - Imperial Units

### Example - Speed of Sound in Air

The individual gas constant for air is *286.9 J/kgK* and the ratio of specific heat is *1.4*. The speed of sound at *0 ^{o}C (273.15 K)* can be calculated as

* c = (1.4 (286.9 J/kgK) (273.15 K)) ^{1/2} *

* = 331.2 m/s*

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