Convert frequency to wavelength and wavelength back to frequency using the speed of light, c = 299,792,458 m/s.
Frequency and wavelength are linked by the speed of light: wavelength equals c divided by frequency, with c = 299,792,458 metres per second in a vacuum. That vacuum value is used here, which is also a close approximation for radio waves in air. The speed is slightly lower in air than in a vacuum and substantially lower in cables, where a velocity factor (often around 0.66 to 0.85) applies — for a cable, multiply the wavelength shown here by that velocity factor to get the wavelength in the cable. Treat this converter as the vacuum and air approximation it states.
What formula links frequency and wavelength? Wavelength in metres equals the speed of light divided by frequency in hertz: λ = c / f, with c = 299,792,458 m/s. Frequency is the reverse: f = c / λ.
Is the result the same inside a cable? No. Signals travel slower in cables according to the cable velocity factor, so the wavelength in a cable is shorter than the vacuum or air value shown here by that factor.