Wavelength and Frequency Calculator
Convert between radio frequency and wavelength.
Calculate quarter-wave and half-wave antenna dimensions for any amateur radio band.
The relationship between frequency and wavelength is fundamental to all radio antenna design.
Formula: λ = c / f
Where λ is wavelength (meters), c is the speed of light (299,792,458 m/s ≈ 300 Mhz·m), and f is frequency in Hz.
Simplified: λ (meters) = 300 / f (MHz)
Common antenna dimensions:
- Full wavelength: λ = 300 / f(MHz)
- Half-wave dipole (free space): λ/2 = 150 / f(MHz)
- Half-wave dipole (wire, velocity factor 0.95): 142.5 / f(MHz)
- Quarter-wave vertical: λ/4 = 75 / f(MHz)
Amateur radio band wavelengths:
- 160 m band: 1.8–2.0 MHz, λ = 150–167 m
- 80 m band: 3.5–4.0 MHz, λ = 75–86 m
- 40 m band: 7.0–7.3 MHz, λ = 41–43 m
- 20 m band: 14.0–14.35 MHz, λ = 20.9–21.4 m
- 15 m band: 21.0–21.45 MHz, λ = 14.0–14.3 m
- 10 m band: 28.0–29.7 MHz, λ = 10.1–10.7 m
- 2 m band: 144–148 MHz, λ = 2.03–2.08 m
- 70 cm band: 420–450 MHz, λ = 0.667–0.714 m
Velocity factor in coaxial cable is typically 0.66–0.80, meaning the electrical wavelength inside coax is shorter than in free space. This matters for designing coaxial stubs and phased arrays.
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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