Frequency to Wavelength Calculator
Calculate the wavelength of a radio signal, light or sound from its frequency — or the frequency from a wavelength.
How to use the Frequency to Wavelength Calculator
- Choose frequency → wavelength or the reverse.
- Enter the value and unit.
- Choose the type of wave (light/radio or sound).
How it works
Wavelength = wave speed ÷ frequency. Radio waves and light travel at about 299,792 km/s, so a 100 MHz FM signal has a 3 m wavelength and 2.4 GHz Wi-Fi about 12.5 cm. Sound is much slower — about 343 m/s in air at 20 °C — so a 440 Hz note has a wavelength of about 78 cm.
Examples
| Signal | Frequency | Wavelength |
|---|---|---|
| AM radio | 1 MHz | 300 m |
| FM radio | 100 MHz | 3 m |
| Wi-Fi | 2.4 GHz | 12.5 cm |
| Wi-Fi | 5 GHz | 6 cm |
| Middle A (sound in air) | 440 Hz | 78 cm |
| Green light | 563 THz | 532 nm |
Frequently asked questions
What is the wavelength of 2.4 GHz?
About 12.5 cm.
How long should an antenna be?
A quarter-wave antenna is about ¼ of the wavelength — about 75 cm for 100 MHz.
What is the wavelength of 440 Hz?
About 0.78 m in air.
Do all waves travel at the speed of light?
Electromagnetic waves do; sound travels much slower and depends on the medium.