Frequency & Wavelength Calculator
Turn a frequency into its wavelength, then get half-wave and quarter-wave element lengths — with a velocity factor so a cut element resonates on frequency.
From a band to a buildable element
Wavelength is the ruler all antenna work is measured against. Once you know it for your band, the physical size of a dipole, a whip, a ground plane, or the spacing of a Yagi's elements all fall out of it. It is the first number to reach for whether you are cutting wire for HF or laying out a microwave patch.
Pair the element length with the Antenna Gain Converter to see how gain and beamwidth trade off, and feed the frequency into the Free-Space Path Loss Calculator to see the loss that band faces over distance.
Frequently Asked Questions
How do frequency and wavelength relate?
A radio wave's wavelength is the speed of light divided by its frequency: λ = c / f, with c = 299,792,458 m/s. Higher frequencies have shorter wavelengths. As handy anchors, roughly 300 MHz is a 1 m wave, 2.4 GHz is about 12.5 cm, and 100 MHz FM is about 3 m. This tool does the division for you and expresses the answer in metres, centimetres, or millimetres.
Why does the calculator give antenna lengths too?
Antenna elements resonate when they are a specific fraction of a wavelength. The half-wave dipole (λ/2) and the quarter-wave monopole or whip (λ/4) are the two most common resonant lengths, so knowing the wavelength immediately tells you how long to cut an element. The tool shows both alongside the free-space wavelength.
What is the velocity factor and why is the element shorter than λ/4?
A wave travels a few percent slower along a real conductor than through free space, so a physical element resonates a little short of the free-space figure. The velocity factor (typically around 0.95 for thin wire, lower for insulated or thick elements) scales the length down to match. Set it to 1 to see the pure free-space length, or to your material's value for a buildable length.
Can I cut an antenna to exactly this length and be done?
Treat it as a starting length. The real resonant point shifts with conductor diameter, insulation, nearby metal, height above ground, and end effects, so a cut element almost always needs trimming. Cut slightly long, then measure with an antenna analyzer or VNA and trim to the lowest SWR. The calculator gets you close; measurement finishes the job. Educational estimate, not a build guarantee.
Element lengths are starting points — real resonance shifts with conductor and surroundings, so trim and measure with an analyzer. Educational estimate, not a build guarantee.