# Speed of Sound Calculator

Calculate the speed of sound in air, water, steel, or helium at any temperature. Convert between m/s, km/h, and mph. Free online physics calculator.

## What this calculates

The speed of sound depends on the medium through which it travels and the temperature. In air at 20°C, sound travels at approximately 343 m/s (1,235 km/h). This calculator lets you find the speed of sound in various media and convert between common units.

## Inputs

- **Medium** — options: Air, Water (fresh, 25°C), Steel, Helium, Custom (enter speed) — Select the medium through which sound travels.
- **Temperature** (°C) — min -273.15 — Temperature in °C (affects speed in air and helium).
- **Custom Speed** (m/s) — min 0 — Enter a custom speed of sound in m/s (used only when 'Custom' is selected).

## Outputs

- **Speed of Sound** (m/s) — Speed of sound in meters per second.
- **Speed of Sound** (km/h) — Speed of sound in kilometers per hour.
- **Speed of Sound** (mph) — Speed of sound in miles per hour.
- **Mach 1 at This Speed** (m/s) — Mach 1 equals the speed of sound in the selected medium.

## Details

Sound is a mechanical wave that requires a medium to propagate. Its speed depends on the medium's density and elasticity. In general, sound travels fastest through solids (steel ≈ 5,960 m/s), slower through liquids (water ≈ 1,480 m/s), and slowest through gases (air ≈ 343 m/s at 20°C).

In air, the speed of sound increases with temperature according to the approximation v = 331.3 + 0.606T, where T is in degrees Celsius. This is because higher temperatures mean faster-moving air molecules, enabling quicker transmission of pressure waves. In helium, sound travels nearly three times faster than in air due to helium's much lower molecular mass.

Mach number expresses an object's speed relative to the local speed of sound. Mach 1 is the speed of sound; Mach 2 is twice the speed of sound. The sound barrier (the dramatic increase in aerodynamic drag near Mach 1) was first broken by Chuck Yeager in 1947. Understanding the speed of sound is fundamental in acoustics, aeronautics, and seismology.

## Frequently Asked Questions

**Q: Why does sound travel faster in solids than in air?**

A: Solids have tightly packed molecules with strong intermolecular bonds, allowing vibrations to transfer much more quickly. The higher stiffness (bulk modulus) of solids more than compensates for their greater density.

**Q: How does temperature affect the speed of sound in air?**

A: Higher temperatures increase the kinetic energy of air molecules, making them vibrate and transmit pressure waves more quickly. The speed increases by about 0.6 m/s for each 1°C rise in temperature.

**Q: What is Mach 1?**

A: Mach 1 is the speed of sound in the local medium and conditions. At sea level and 20°C in air, Mach 1 ≈ 343 m/s (1,235 km/h). At higher altitudes where air is colder, Mach 1 is lower.

**Q: Does humidity affect the speed of sound?**

A: Yes, slightly. Humid air is less dense than dry air (water vapor is lighter than nitrogen and oxygen), so sound travels slightly faster in humid air, typically a 0.1-0.6% increase.

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Source: https://vastcalc.com/calculators/physics/speed-of-sound
Category: Physics
Last updated: 2026-04-21