Wavelength Calculator
The wavelength of a wave from its frequency, using the speed of light.
Result
Wavelength (m)
2.9979
Wavelength (cm)
299.79
How it works
Wavelength and frequency are inverse partners linked by speed: λ = c ÷ frequency, with c ≈ 3 × 10⁸ m/s for electromagnetic waves in a vacuum. Higher frequency means a shorter wave. That inverse relation spans the whole spectrum. FM radio near 100 MHz has waves about 3 m long; Wi-Fi at 2.4 GHz about 12.5 cm; visible light a few hundred nanometres; X-rays smaller than an atom. The physics is identical throughout — only the scale changes. Wavelength dictates antenna size, which is why radio masts are huge and a Wi-Fi antenna fits in a phone: an efficient antenna is a simple fraction of the wave it handles. For sound the same formula applies but with the speed of sound, about 343 m/s in air, so you must use that value instead of c.
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Frequently asked questions
What is the wavelength of Wi-Fi?
At 2400 MHz it is about 12.5 cm — enter 2400 to check.
Does this work for sound?
Sound uses its own speed (~343 m/s in air), not the speed of light, so this tool is for electromagnetic waves.
Why do low frequencies pass through walls better?
Longer waves bend around and through obstacles more easily than short ones. That is why 2.4 GHz Wi-Fi reaches further inside a building than 5 GHz, and why you hear a neighbour's bass through a wall while the melody is lost.
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