Sound travels faster in warmer air because the molecules move faster: about 331 m/s at 0 °C and 343 m/s at 20 °C. In water it is more than four times faster. Pilots, musicians and sonar operators all depend on knowing it.
How to use the Speed of Sound Calculator
- Medium
- Temperature
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the medium and enter the temperature.
Inputs explained
| Field | What to enter |
|---|---|
| Medium | Choose one: Dry air, Fresh water |
| Temperature | Units: °C, °F, K |
Example values
How the main result changes when Temperature changes and everything else stays at the example values above:
| Temperature (°C) | Speed of sound (m/s) |
|---|---|
| 10 | 337.3099 |
| 15 | 340.2751 |
| 20 | 343.2146 |
| 25 | 346.1292 |
| 30 | 349.0194 |
| 40 | 354.7293 |
Formula
Air: v = 331.3·√(1 + T/273.15) m/s · Water: v = 1402.385 + 5.0388T − 0.05799T² + 3.287×10⁻⁴T³ − 1.399×10⁻⁶T⁴ + 2.788×10⁻⁹T⁵
Worked example
Inputs: Medium: Dry air; Temperature: 20 °C.
Results: Speed of sound = 343.21462 m/s; Time to travel 1 km = 2.9136 s.
Key terms
- Mach number
- Speed divided by the local speed of sound.
Frequently asked questions
Why is sound faster in warm air?
Warmer molecules move faster and pass the disturbance on more quickly.
Does air pressure affect the speed of sound?
Not significantly for an ideal gas, since temperature dominates.
Why is sound faster in water?
Water is much stiffer (less compressible) than air.
How fast is Mach 1?
The local speed of sound, about 1,235 km/h at 20 °C.