The dipole is one of the most popular antennas, especially in the low HF bands. The formula for a half-wave dipole is 468 divided by the frequency. Here is a dipole length chart.

Frequency — Quarter Wavelength (ft) — Total Length (ft)

1.9 — 123.1 — 246.2
3.75 — 62.4 — 124.8
5.36 — 43.7 — 87.4
7.15 — 32.7 — 65.4
10.125 — 23.1 — 46.2
14.175 — 16.5 — 33
18.1 — 12.9 — 25.8
21.225 — 11 — 22
24.9 — 9.4 — 18.8
28.350 — 8.25 — 16.5
52.0 — 4.5 — 9