Wavelength Calculator

Enter a frequency to find the wavelength of a light, radio or sound wave.

This result is an estimate only. Double-check important figures before relying on them.

How it is calculated

Frequency in hertz = value × 1, 1,000, 1,000,000 or 1,000,000,000
Wavelength = speed ÷ frequency
Period = 1 ÷ frequency

To change between related units, see the angular velocity calculator.

Worked example

A 100 MHz FM radio station:

λ = 299,792,458 ÷ 100,000,000 = 2.9979 m

Why your number may differ

The speed of sound changes with temperature (about 0.6 m/s for each °C), and light slows down in glass or water. The calculator uses fixed speeds for air and vacuum.

Frequently asked questions

What is the wavelength formula?

Wavelength = wave speed ÷ frequency. For light and radio, the speed is 299,792,458 m/s. For sound in air at 20 °C it is about 343 m/s.

Why does sound use a different speed?

Sound is a pressure wave in air and travels far slower than light. It also changes with temperature.

What is the wavelength of Wi-Fi?

At 2.4 GHz it is about 12.5 cm, and at 5 GHz about 6 cm.