Wavelength & Frequency Calculator
Convert between wavelength and frequency using c = λ·f, for light, sound, or any wave speed you set.
Enter a wavelength or a frequency and leave the other blank — the calculator fills in the missing one using c = λ·f.
Wavelength
599,584.916m
Frequency
500Hz
How it works
Every wave obeys the same tidy rule: its speed equals its wavelength times its frequency, c = λ·f. Pin down two of those and the third falls out. Enter a frequency and get the wavelength, or the other way round.
For light and other electromagnetic waves, the speed is fixed at 299,792,458 m/s in a vacuum — pick the Light option and it's filled in for you. That's why a 500 THz light wave has a wavelength of about 600 nanometers, right in the visible range.
Sound is much slower, roughly 343 m/s in room-temperature air, so a 500 Hz tone stretches out to about 0.69 meters. Switch to the Sound preset for that, or choose Custom to type any wave speed — useful for waves on strings, water, or sound through other materials.
Frequently asked questions
What speed should I use?
For light or radio waves in a vacuum, use the speed of light (the Light preset). For sound in air, use about 343 m/s (the Sound preset). For anything else — waves on a rope, ripples on water — type the medium's wave speed in the Custom box.
Why is the light wavelength so tiny?
Because light is fast and everyday frequencies are enormous. A 500 THz signal is 500 trillion cycles per second, so each wave is only a few hundred nanometers long. That small scale is exactly why visible light interacts with atom-sized things.
Does this work for frequencies in THz or GHz?
Enter frequency in hertz for a direct result — 1 GHz is 1,000,000,000 Hz and 1 THz is 1,000,000,000,000 Hz. Convert to plain hertz first and the wavelength will come out in meters.