Microwaves are a form of electromagnetic waves with wavelengths ranging from one millimeter (mm) to one meter (m). They fall between infrared radiation and radio waves on the electromagnetic spectrum.

The size of a microwave wavelength depends on its frequency. Microwaves with shorter wavelengths have higher frequencies and vice versa. The higher the frequency, the smaller the wavelength.

For example, a microwave with a wavelength of one millimeter (1 mm) has a frequency of 300 gigahertz (GHz), while a microwave with a wavelength of one meter (1 m) has a frequency of 300 megahertz (MHz).

Common household microwave ovens typically operate at a frequency of 2.45 GHz, which corresponds to a wavelength of about 12.2 centimeters (cm) or 4.8 inches (in).