Sound travels faster in warm air because molecules move faster. It is about 343 m/s at 20 °C.
How to use the Speed of Sound Calculator
- Air temperature
Results update as you type, and every field accepts the units shown in its menu.
How it works
The speed at 0 °C is scaled by the square root of absolute temperature.
What each result means
- Speed of sound = 331.3 × sqrt(1 + [Air temperature]÷273.15)
- Mach 1 in km/h = [Speed of sound] × 3.6
Example values
How the main result changes when Air temperature changes and everything else stays at the example values above:
| Air temperature (°C) | Speed of sound (m/s) |
|---|---|
| 10 | 337.31 |
| 15 | 340.28 |
| 20 | 343.21 |
| 25 | 346.13 |
| 30 | 349.02 |
| 40 | 354.73 |
Formula
v = 331.3 × √(1 + T(°C) ÷ 273.15)Worked example
Inputs — Air temperature: 20 °C.
Results — Speed of sound = 343.21 m/s; Mach 1 in km/h = 1,235.6 km/h.
Frequently asked questions
How far away is lightning?
Count seconds between flash and thunder and multiply by about 343 m.
Does humidity matter?
Slightly; humid air carries sound a little faster.
What formula does the Speed of Sound Calculator use?
v = 331.3 × √(1 + T(°C) ÷ 273.15).