Wavelength and Frequency Calculator

The wave equation is c = f x lambda, where c is the wave speed, f is the frequency and lambda is the wavelength. Rearranged, lambda = c / f and f = c / lambda, which is how this tool solves for whichever value you leave out.

The exact speed of light in a vacuum, 299,792,458 metres per second, is the default wave speed. That value is why 100 MHz maps to a wavelength of 2.99792458 metres.

Photon energy is E = h x f, where h is the Planck constant 6.626 x 10^-34 joule-seconds and f is the frequency in hertz. The result is shown in joules, for example 6.62600e-26 J at 100 MHz.

Wavelength in metres or nanometres, and frequency in hertz, megahertz or gigahertz. The input unit and the two display units are set independently, and everything is converted to SI before the calculation.

Frequency and wavelength are inversely related, so a zero value would require dividing by zero, which is undefined. Zero and negative inputs are rejected with a short message.

Results are rounded to twelve significant figures to remove floating point noise, then shown plainly for readable magnitudes and in scientific notation with five decimals when a value is very large or very small.

Yes. The Show wavelength in and Show frequency in menus set the display units separately from the input, so you can enter 500 nm and read the frequency in hertz or gigahertz.

The engine supports a vacuum medium and defaults to the speed of light, so it is exact for electromagnetic waves. For sound or other media you would need a different wave speed, which the tool interface does not expose.

Yes. Everything runs locally in your browser, so nothing you enter is uploaded. The tool is free and works offline once the page has loaded.