Wavelength ↔ Frequency
Convert
Choose a direction; the other value is computed live.
Result
How to use this calculator
Wavelength and frequency are two ways of describing the same electromagnetic wave. They're related by the speed of light: λ = c / f, where c ≈ 300,000,000 m/s. Choose a direction (frequency → wavelength, or the reverse), enter one value with its unit, and the calculator computes the other live.
What it means in a real circuit
For 144 MHz (the 2-meter amateur band), λ = 3×10⁸ / 144×10⁶ ≈ 2.08 m. Knowing the wavelength is the first step in sizing any antenna — a half-wave dipole is roughly λ/2 long. Use this to convert between the frequency you're working with and the physical size of the wave, which is what your antenna and feedline must be built to.
Definitions
Frequency (f): cycles per second (Hz). Wavelength (λ): the physical distance of one cycle (m). Speed of light (c): ≈ 299,792,458 m/s in free space. RF: typically 3 kHz – 300 GHz.
Design tips
Always work in meters for antenna sizing, then convert to the unit that's convenient to measure. For very high frequencies (GHz), wavelengths are centimeters or less — precision matters. Remember that the speed of light is slightly slower in a dielectric (e.g. coax), so feedline electrical length differs from physical length.
Common mistakes
Mixing up Hz and MHz (a factor of 1,000,000). Forgetting that wavelength is in meters, not centimeters, in the formula. Assuming the speed in a cable equals c (it's ~0.66–0.9·c depending on dielectric).
Component-selection / practical advice
This is a pure conversion — no components. But it's the basis for choosing antenna element lengths, feedline electrical length, and filter component values.
Limitations
Assumes free-space propagation (c = 299,792,458 m/s). In a medium with refractive index n, the speed is c/n and the wavelength is shorter. For near-field or waveguide cases, the simple λ = c/f relationship doesn't fully apply.
Example use cases
Sizing a dipole for 144 MHz; converting a filter's center frequency to a physical dimension; checking that a feedline length is an electrical multiple of λ/4; verifying a VSWR meter's frequency against its wavelength.
Frequently asked questions
λ = c / f, where c is the speed of light. The calculator normalizes your input to Hz and meters, then computes the other quantity.
Any — the dropdown handles Hz/kHz/MHz/GHz and m/cm/mm. Internally everything is normalized to Hz and meters.
Theoretical (free space). In a cable or near a ground plane, the effective wavelength differs.
Antenna elements are sized as fractions of the wavelength (e.g. a half-wave dipole ≈ λ/2). Getting λ right is the first step in any antenna design.
Confusing Hz and MHz (a factor of a million), or forgetting that λ is in meters in the formula.