This tool converts from **Wavelength** in nm, um, mm, cm, m, inches or feet to **Frequency** in Hz, kHz, MHz, GHz.

**Formula**

Frequency **f** is given by the formula

**f = c/λ**

where, **c** is the speed of light and **λ** is the wavelength. As the wavelength increases the frequency decreases.

In a vacuum, the speed of light is **c = 299,792,458 meters/second**. It is slower in other media such as in glass for instance where the speed is 200,000,000 meters/second. Change the value of **c** in the calculator above to calculate the frequency in this case.

For a fixed value of wavelength, as c increases, so does f.

The picture below shows the wavelength (**λ**) of a sine wave

## Frequency and Wavelength in RF Engineering

Most Radio engineers are used to referring to regions of the electromagnetic spectrum in terms frequency – for instance the Wi-Fi band is 2.4 GHz and 5 GHz.

The exception is when you get to lower frequencies in HF and VHF. At these bands, hobbyists and technologists refer to wavelength. For instance the 2 meter and 70 cm bands. It can be a little confusing sometimes.

This calculator clears up that confusion to make the conversion between wavelength and frequency easy.