Dipole antenna length chart

Half-wave dipole and quarter-wave vertical lengths for every amateur band from 160 m to 70 cm, in metres, feet and feet-inches, at the middle of the band.

Indicative values; verify before use.

Half-wave dipole and quarter-wave lengths, 160 m to 70 cm

Shortening factor k = 0.95 (end effect of a thin bare wire). Dipole total = k × λ / 2; each dipole leg and a quarter-wave vertical radiator = k × λ / 4; λ = 299.792458 / f(MHz) metres. Calculated at the centre of each band.

Band	ITU region	Centre MHz	Half-wave dipole, total			Dipole leg = ¼-wave vertical			Band edges MHz
Band	ITU region	Centre MHz	m	ft	ft-in	m	ft	ft-in	Band edges MHz
160 m	1	1.830	77.81	255.3	255′ 3½″	38.91	127.6	127′ 7¾″	1.810–1.850
160 m	2, 3	1.900	74.95	245.9	245′ 10¾″	37.47	122.9	122′ 11¼″	1.800–2.000
80 m	1	3.650	39.01	128.0	128′ 0″	19.51	64.00	64′ 0″	3.500–3.800
80 m	3	3.700	38.49	126.3	126′ 3¼″	19.24	63.13	63′ 1½″	3.500–3.900
80/75 m	2	3.750	37.97	124.6	124′ 7″	18.99	62.29	62′ 3½″	3.500–4.000
60 m	all	5.359	26.57	87.18	87′ 2¼″	13.29	43.59	43′ 7″	5.3515–5.3665
40 m	1, 3	7.100	20.06	65.80	65′ 9¾″	10.03	32.90	32′ 10¾″	7.000–7.200
40 m	2	7.150	19.92	65.34	65′ 4″	9.958	32.67	32′ 8″	7.000–7.300
30 m	all	10.125	14.06	46.14	46′ 1¾″	7.032	23.07	23′ 0¾″	10.100–10.150
20 m	all	14.175	10.05	32.96	32′ 11½″	5.023	16.48	16′ 5¾″	14.000–14.350
17 m	all	18.118	7.860	25.79	25′ 9½″	3.930	12.89	12′ 10¾″	18.068–18.168
15 m	all	21.225	6.709	22.01	22′ 0¼″	3.355	11.01	11′ 0″	21.000–21.450
12 m	all	24.940	5.710	18.73	18′ 8¾″	2.855	9.37	9′ 4½″	24.890–24.990
10 m	all	28.850	4.936	16.19	16′ 2¼″	2.468	8.10	8′ 1¼″	28.000–29.700
6 m	1	51.000	2.792	9.16	9′ 2″	1.396	4.58	4′ 7″	50.000–52.000
6 m	2, 3	52.000	2.738	8.98	8′ 11¾″	1.369	4.49	4′ 6″	50.000–54.000
4 m	1*	70.250	2.027	6.65	6′ 7¾″	1.014	3.33	3′ 4″	70.000–70.500
2 m	1	145	0.982	3.22	3′ 2¾″	0.491	1.61	1′ 7¼″	144–146
2 m	2, 3	146	0.975	3.20	3′ 2½″	0.488	1.60	1′ 7¼″	144–148
1.25 m	2	223.5	0.637	2.09	2′ 1″	0.319	1.05	1′ 0½″	222–225
70 cm	all	435	0.327	1.07	1′ 1″	0.164	0.54	0′ 6½″	430–440

* 4 m is not in the ITU table but is allocated in many Region 1 countries. The classic 468 / f(MHz) feet rule equals k ≈ 0.952, so it gives lengths within 0.2 % of this chart. Band edges differ by country and licence class; check your own band plan. US: 160 m is 1.8–2.0 MHz, 70 cm is 420–450 MHz (centre also 435 MHz). For any other frequency or factor, use the antenna length calculator.

Cut the wire a few percent long, measure SWR and trim. Insulated wire, thick conductors, low height and nearby objects all make the resonant length shorter. The factor here is for the antenna wire, not the velocity factor of coaxial cable.

Sources (checked 2026-10-31):

Amateur band edges by ITU region: https://en.wikipedia.org/wiki/Amateur_radio_frequency_allocations
c = 299 792 458 m/s, exact (SI defining constant): https://physics.nist.gov/cgi-bin/cuu/Value?c
Half-wave dipole ≈ λ / 2, shortened by end effect: https://en.wikipedia.org/wiki/Dipole_antenna
Quarter-wave vertical (monopole) ≈ λ / 4: https://en.wikipedia.org/wiki/Monopole_antenna
1 ft = 0.3048 m exactly: https://en.wikipedia.org/wiki/Foot_%28unit%29
468 / f rule of thumb, attributed to the ARRL Antenna Book (book not checked by us): https://www.66pacific.com/calculators/dipole-antenna-length-calculator.aspx

Ohmsums. Indicative values; verify before use.