# Speed of Sound Calculator

URL: https://speedycalculator.com/calculators/physics/speed-of-sound/
Last updated: 2026-10-25

> The speed of sound calculator estimates how fast sound travels in dry air at a given temperature, using v ≈ 331.3 √(1 + T ÷ 273.15). It also gives how far sound travels in one second.

## Inputs

- Air temperature (°C, °F, K)

## Results

- Speed of sound
- Mach 1 in km/h

## Formula

```
v = 331.3 × √(1 + T(°C) ÷ 273.15)
```

## Explanation

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)10337.3115340.2820343.2125346.1330349.0240354.73

## 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.

## FAQ

**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).