Speed of Sound Calculator
This speed of sound calculator determines the speed of sound in air and fresh water based on temperature. The higher the temperature, the faster sound travels.
Speed of Sound in Air
Air behaves nearly as an ideal gas. The speed of sound in air is calculated using the formula:
cair = 331.3 × √(1 + T / 273.15)
where T is the temperature in °C. At 20 °C, the speed of sound in air is approximately 343 m/s (1,235 km/h or 1,125 ft/s).
Notably, the speed of sound in gas depends only on temperature — not on pressure or density.
Speed of Sound in Water
The speed of sound in fresh water is significantly higher than in air. At 20 °C, sound travels at approximately 1,482 m/s — about 4.3× faster than in air.
The calculator uses the Marczak freshwater equation (valid for 0 – 100 °C):
cwater = 1402.388 + 5.038813·T − 0.0579136·T² + 0.00032872·T³ − 1.3988·10⁻⁶·T⁴ + 2.788·10⁻⁹·T⁵
Unit Conversion Table
| From | To m/s | To km/h | To ft/s | To mph | To knots |
|---|---|---|---|---|---|
| 1 m/s | 1 | 3.6 | 3.281 | 2.237 | 1.944 |
Frequently Asked Questions
- What is the speed of sound at room temperature?
- At 20 °C (68 °F), the speed of sound in air is approximately 343 m/s, 1,235 km/h, 1,125 ft/s, 767 mph, or 667 knots.
- Does humidity affect the speed of sound?
- Yes, but only slightly — the effect is negligible for most practical purposes. Temperature is the dominant factor.
- Why is sound faster in water than in air?
- Water is much less compressible than air and has a higher bulk modulus, allowing pressure waves to travel faster.
- What is the speed of sound in mph?
- At 20 °C, the speed of sound in air is approximately 767 mph. At 0 °C it is about 740 mph.
- What temperature does sound travel fastest in water?
- In fresh water, sound speed peaks around 74 °C (approximately 1,555 m/s), then slightly decreases at higher temperatures.