📏 Antenna length calculator
Dipole, ¼-wave, ⅝-wave, loop and J-pole cut lengths for any frequency, in feet or metres.
Frequency
Cut lengths
- Half-wave dipole (total)
- 3′ 2.5″
- 38.47 in · each leg 1′ 7.2″
- ¼-wave vertical
- 1′ 7.2″
- 19.23 in · radials the same length or longer
- ⅝-wave vertical
- 4′ 0.1″
- 48.08 in · needs a matching coil at the base
- Full-wave loop
- 6′ 10.6″
- 82.60 in · total wire, any shape
- J-pole: ¾-wave element
- 4′ 9.7″
- 57.70 in · ¼-wave stub 1′ 7.2″
- Free-space wavelength
- 6′ 8.8″
- 80.84 in · ½ λ 3′ 4.4″
Cut 2-3% long, hang the antenna where it will live, then trim both ends a little at a time for lowest SWR. Insulated wire, nearby metal and height above ground all pull the resonant point down, so the number here is a starting point, not the finish line.