Wavelength Calculator
Solve λ = v ÷ f — enter the frequency and wave speed to get the wavelength, auto-scaled to km, m, mm, µm or nm.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
Default is light in vacuum; use ≈ 343 for sound in air
2.997925m
Wavelength 2.997925 mShow steps
- Frequency in hertz: f = 100 MHz × 1,000,000 = 100,000,000 Hz.
- λ = v ÷ f = 299,792,458 m/s ÷ 100,000,000 Hz = 2.997925 m.
- In a convenient unit: wavelength λ = 2.997925 m.
How to use the wavelength calculator
- 1Pick the frequency unit — Hz, kHz, MHz or GHz — and enter the frequency.
- 2Keep the default wave speed for light and radio waves; enter ≈ 343 m/s for sound in air.
- 3Read the wavelength in a convenient unit (km, m, mm, µm or nm), with the full working under Show steps.
Why antennas are the size they are
Many antennas work best at a quarter of the wavelength. FM radio at 100 MHz has λ ≈ 3 m, so car aerials are around 75 cm; Wi-Fi at 2.4 GHz has λ ≈ 125 mm, which is why its antennas fit inside a laptop. If a result looks odd, check the frequency unit first — mixing up Hz and MHz shifts the wavelength by a factor of a million.
Frequently asked questions
What is the wavelength formula?
Wavelength is wave speed divided by frequency: λ = v ÷ f. Rearranged, speed v = λ × f and frequency f = v ÷ λ.
What wave speed should I enter?
For light and radio waves in vacuum or air use 299 792 458 m/s (the default). For sound in air at room temperature use about 343 m/s; in water sound travels at roughly 1480 m/s.
What is the wavelength of Wi-Fi?
2.4 GHz Wi-Fi has a wavelength of about 125 mm (12.5 cm) and 5 GHz Wi-Fi about 60 mm. Enter 2.4 with the GHz unit and keep the default speed of light to reproduce it.
Does a higher frequency mean a shorter wavelength?
Yes. At a fixed wave speed, wavelength and frequency are inversely proportional: doubling f halves λ. That is why low bass notes have waves metres long while treble sits at centimetres.