Case 1
- Air temperature (°C)
- 20°C
343.42m/s
Open with these valuesSpeed of Sound Calculator
343.42m/s
Result: 343.42 m/sSound travels through dry air at 331.3 m/s at freezing point and gains about 0.606 m/s for every degree Celsius: 343.42 m/s at 20 °C. Warmer air means faster molecules and a quicker relay. Humidity and altitude shift the figure slightly, so treat it as a close everyday approximation.
The numbers at a glance
| Air temperature (°C) (°C) | Result (m/s) |
|---|---|
| 0.00 | 331.30 |
| 5.00 | 334.33 |
| 10.00 | 337.36 |
| 15.00 | 340.39 |
| 20.00Your value | 343.42 |
| 25.00 | 346.45 |
| 30.00 | 349.48 |
| 35.00 | 352.51 |
| 40.00 | 355.54 |
Worked examples
Case 2
- Air temperature (°C)
- 0°C
331.30m/s
Open with these valuesCase 3
- Air temperature (°C)
- -40°C
307.06m/s
Open with these valuesHow it's calculated
v = 331.3 + 0.606 × T
- StepEnter the air temperature in degrees Celsius.
- StepEvery degree adds about 0.606 m/s to the 331.3 m/s baseline.
- ResultRead the speed in metres per second — divide a distance by it to get the delay.
Reference table
| Air temperature (°C) | Setting | Speed of sound (m/s) |
|---|---|---|
| -40 | Cruising altitude of an airliner | 307.06 |
| 0 | Freezing point of water | 331.3 |
| 20 | Room temperature | 343.42 |
| 25 | Warm summer day | 346.45 |
| 100 | Boiling point of water | 391.9 |
Questions
How do I calculate the speed of sound in air?
Use the dry-air approximation v = 331.3 + 0.606 × T, where T is the air temperature in °C and v comes out in metres per second. At 20 °C that gives 331.3 + 0.606 × 20 = 343.42 m/s. Add about 0.6 m/s for every degree the air warms up.
Why does temperature change the speed of sound?
Sound travels by molecules bumping into their neighbours. Warmer air has faster-moving molecules, so the disturbance passes along more quickly. Each extra degree Celsius adds roughly 0.6 m/s, which is why sound is about 331 m/s at 0 °C but around 343 m/s at 20 °C.
What is the speed of sound at 0 °C?
At 0 °C the formula gives 331.3 + 0.606 × 0 = 331.3 m/s. This is the intercept of the linear approximation — the speed of sound in dry air at the freezing point of water. Reference works quote values between 331.3 and 331.6 m/s, so the last decimal is not settled.
Do humidity and altitude affect the result?
Slightly — this formula assumes dry air, but humid air is a little less dense and carries sound marginally faster, usually well under 1 percent. Altitude changes the speed mainly through temperature, not pressure directly. For everyday use the dry-air figure is a close approximation.
What can I use the speed of sound for?
Estimating distances from echoes and thunder is the classic use: sound covers about 343 m every second at 20 °C, so a thunderclap heard 3 seconds after the lightning is roughly 1 km away. It also matters for music, acoustics, and timing sonar or ultrasonic sensors.
Sources and last check
Information, not professional advice.