About this tool
Pick a wave speed — the speed of light, the speed of sound, or your own value — then enter either a frequency or a wavelength to get the other, plus the period. For light it also shows the photon energy. It all runs in your browser.
Frequently asked questions
How are wavelength and frequency related?
They are linked by wave speed: wavelength = speed / frequency. Higher frequencies mean shorter wavelengths for a fixed speed.
How is photon energy calculated?
For light it uses E = h × f, where h is Planck's constant, shown in both joules and electronvolts (eV).