Antenna Length Calculator

About this calculator

Radio wavelength relates to frequency by λ = c/f; since the speed of light c ≈ 3×10⁸ m/s, this simplifies to the handy rule λ (meters) = 300 / f (MHz). From that wavelength, this calculator derives the three most common antenna lengths: full-wave (λ), half-wave (λ/2 — the classic dipole), and quarter-wave (λ/4 — the classic ground-plane monopole), often scaled by a velocity factor of roughly 0.95 to account for a real wire's end effects.

Amateur (ham) radio operators use these formulas to cut dipole and monopole wire antennas tuned to a specific band, and RF and broadcast engineers use the same relationship when designing antennas for transmitters and receivers across the spectrum, from HF ham bands up through VHF/UHF. Enter a target frequency in MHz to get all three lengths at once.