About the Speed of Sound Calculator
What is the Speed of Sound Calculator?
The speed of sound in air rises with temperature – about 0.6 m/s per degree. This calculator finds it for any air temperature, or for water, steel, glass and wood.
Enter a delay to work out how far away lightning struck, or the distance to a wall from its echo.
How to use the Speed of Sound Calculator
- Medium (sample: Dry air (uses temperature))
- Air Temperature (°C) (sample: 20)
- Echo or Thunder Delay (s, optional) (sample: 3)
- Press Calculate Speed of Sound (results also refresh as you type). The result card shows the Speed of Sound, along with In km/h, Distance to a storm (thunder delay), Distance to a reflecting wall (echo delay ÷ 2) and Time to travel 1 km.
Formula used
v = 331.3 × √(1 + T ÷ 273.15) m/s
- T = air temperature in °C
- Thunder distance = v × delay
- Echo distance = v × delay ÷ 2
Sound travels about 4 times faster in water and 17 times faster in steel than in air.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Medium | Dry air (uses temperature) |
| Air Temperature (°C) | 20 |
| Echo or Thunder Delay (s, optional) | 3 |
| Result | Value |
|---|---|
| Speed of Sound | 343.21 m/s |
| In km/h | 1,235.6 km/h |
| Distance to a storm (thunder delay) | 1.03 km |
| Distance to a reflecting wall (echo delay ÷ 2) | 514.8 m |
| Time to travel 1 km | 2.914 s |
Tips for using the Speed of Sound Calculator
- Count the seconds between lightning and thunder and divide by 3 for the distance in km.
- Humidity raises the speed of sound slightly.