Speed of Sound Calculator (Air & Gases, by Temperature)
By Santaji GadepatilinUpdated November 3, 2026
Sound travels faster in warm gas and in light gas, because the speed depends on temperature and molar mass rather than pressure. This speed of sound calculator uses v = √(γRT/M) for air, nitrogen, CO₂, helium and other gases — the same temperature correction that ultrasonic level transmitters and ultrasonic flow meters apply to their time-of-flight readings.
How to use the speed of sound calculator
Enter the gas’s heat capacity ratio γ, its molar mass and the temperature. The calculator returns the speed of sound and, for the frequency you enter, the wavelength. Values for common gases are in the table below; for mixtures use the mole-weighted molar mass.
Speed of sound formula
v = √(γ R T ÷ M) · λ = v ÷ f
R = 8.314 J/(mol·K), T is the absolute temperature in kelvin and M the molar mass in kg/mol.
Example
Dry air (γ = 1.4, M = 28.965 g/mol) at 20 °C:
- v = √(1.4 × 8.314 × 293.15 ÷ 0.028965) = 343.2 m/s
- Wavelength of a 1 kHz tone = 343.2 ÷ 1000 = 0.3432 m
Speed of sound in common gases
| Gas | γ | M (g/mol) | 0 °C | 20 °C | 100 °C |
|---|---|---|---|---|---|
| Dry air | 1.4 | 28.965 | 331 m/s | 343 m/s | 387 m/s |
| Nitrogen (N₂) | 1.4 | 28.014 | 337 m/s | 349 m/s | 394 m/s |
| Oxygen (O₂) | 1.395 | 31.999 | 315 m/s | 326 m/s | 368 m/s |
| Carbon dioxide (CO₂) | 1.289 | 44.01 | 258 m/s | 267 m/s | 301 m/s |
| Methane (CH₄) | 1.304 | 16.043 | 430 m/s | 445 m/s | 502 m/s |
| Hydrogen (H₂) | 1.405 | 2.016 | 1258 m/s | 1303 m/s | 1470 m/s |
| Helium (He) | 1.667 | 4.0026 | 973 m/s | 1008 m/s | 1137 m/s |
| Argon (Ar) | 1.667 | 39.948 | 308 m/s | 319 m/s | 360 m/s |
Speed of sound in dry air by temperature
| Temperature | Speed | Distance per millisecond |
|---|---|---|
| -40 °C | 306.1 m/s | 306.1 mm/ms |
| -20 °C | 319.0 m/s | 319.0 mm/ms |
| 0 °C | 331.3 m/s | 331.3 mm/ms |
| 10 °C | 337.3 m/s | 337.3 mm/ms |
| 20 °C | 343.2 m/s | 343.2 mm/ms |
| 30 °C | 349.0 m/s | 349.0 mm/ms |
| 40 °C | 354.7 m/s | 354.7 mm/ms |
| 60 °C | 365.9 m/s | 365.9 mm/ms |
| 80 °C | 376.7 m/s | 376.7 mm/ms |
| 100 °C | 387.2 m/s | 387.2 mm/ms |
Practical notes
- An ultrasonic level gauge that assumes 343 m/s but works in 60 °C air reads the distance about 6.6% short — the reason these instruments carry a temperature sensor. See the ultrasonic level calculator.
- Sound travels much faster in liquids and solids (water ≈ 1,480 m/s, steel ≈ 5,900 m/s); this formula applies to gases only.
Frequently asked questions
What is the speed of sound in air?
About 331 m/s at 0 °C and 343 m/s at 20 °C in dry air. It rises by roughly 0.6 m/s for every degree Celsius.
Does pressure change the speed of sound?
Not for an ideal gas. Raising the pressure raises the density by the same factor, so √(γP/ρ) = √(γRT/M) stays the same. Only temperature and gas composition matter.
Why does helium make your voice sound higher?
Sound travels almost three times faster in helium (about 1,000 m/s), so the resonances of your vocal tract shift upward even though your vocal cords vibrate at the same rate.
How does humidity affect the speed of sound?
Water vapour (18 g/mol) is lighter than air, so humid air carries sound slightly faster — about 0.1–0.6% faster at room temperature, depending on humidity.