Coax Loss Chart: Every Cable Type at Every Amateur Band

Manufacturer datasheet attenuation for every cable an amateur is likely to use, at every amateur band, in one printable table.

The short answer

Coaxial cable attenuation is quoted in decibels per 100 feet and rises with frequency. At 14 MHz, RG-58 loses 1.8 dB per 100 feet and LMR-400 class cable loses 0.7 dB. At 440 MHz the same cables lose 10.5 dB and 3.9 dB. Three decibels of loss means half your transmitter power never reaches the antenna, and the same penalty applies on receive.

Units: dB per 100 ft
3 dB: Half the power
Worst case: Thin cable at UHF
Cables listed: 10

Feedline loss is the quietest way to throw away a station, and it is the one specification where the cheap option is genuinely a mistake above 50 MHz. This table is the manufacturer datasheet figures for every cable an amateur is likely to encounter, at every amateur band, so the comparison can be made without hunting through half a dozen catalogues.

Matched attenuation in decibels per 100 feet, by cable and frequency
Cable	160 m	80 m	40 m	20 m	15 m	10 m	6 m	2 m	70 cm	23 cm
RG-174	1.9	2.7	3.9	5.6	7	8.2	11.5	21	40	75
RG-58A/U	0.6	0.9	1.3	1.8	2.3	2.6	3.6	6.4	11.9	22.8
RG-8X (mini-8)	0.5	0.7	1	1.4	1.8	2.1	2.9	5.1	9.1	17
RG-213/U	0.3	0.4	0.6	0.9	1.1	1.3	1.8	3.1	5.9	11
RG-11 (75 ohm)	0.25	0.35	0.5	0.7	0.9	1.05	1.4	2.5	4.6	8.5
LMR-240 / 240-series	0.33	0.46	0.66	0.94	1.16	1.35	1.83	3.19	5.79	10.4
LMR-400 / 400-series	0.17	0.23	0.33	0.47	0.58	0.68	0.92	1.6	2.9	5.2
LMR-600 / 600-series	0.11	0.15	0.21	0.3	0.38	0.44	0.59	1.03	1.87	3.4
1/2 in hardline (LDF4-50A)	0.08	0.11	0.16	0.23	0.29	0.33	0.45	0.79	1.45	2.6
450 ohm window line	0.02	0.03	0.05	0.08	0.1	0.13	0.2	0.5	1.1	2.5

Physical and electrical characteristics
Cable	Impedance	Velocity factor	Diameter	HF power	What it is for
RG-174	50 ohms	0.66	0.1 in	100 W	Thin patch cable. Only for very short jumpers and receive-only runs.
RG-58A/U	50 ohms	0.66	0.195 in	500 W	The cable most starter kits ship. Acceptable on HF at short lengths, poor above 50 MHz.
RG-8X (mini-8)	50 ohms	0.82	0.242 in	800 W	Foam-dielectric half-size cable. The sensible default for HF runs under about 75 ft.
RG-213/U	50 ohms	0.66	0.405 in	1500 W	Solid polyethylene, braided shield, legal-limit capable on HF and physically tough.
RG-11 (75 ohm)	75 ohms	0.78	0.405 in	1500 W	75 ohm cable, cheap in bulk from satellite suppliers. Useful for matching sections, not for a 50 ohm feed.
LMR-240 / 240-series	50 ohms	0.84	0.24 in	800 W	Foam-core, solid-copper-clad center, aluminium-foil plus braid shield. RG-8X size, noticeably lower loss.
LMR-400 / 400-series	50 ohms	0.85	0.405 in	1500 W	The VHF and UHF default. Stiff, so it wants gentle bends and a service loop at the connector.
LMR-600 / 600-series	50 ohms	0.87	0.59 in	1500 W	Half-inch class cable for long UHF runs. Expensive per foot and hard to route indoors.
1/2 in hardline (LDF4-50A)	50 ohms	0.88	0.63 in	1500 W	Corrugated copper hardline. The lowest-loss practical choice, and unforgiving of tight bends.
450 ohm window line	450 ohms	0.91	0.4 in	1500 W	Open-wire balanced line. Almost lossless, but it must stay clear of metal and cannot be coiled.

Converting decibels into watts

What each decibel of loss costs, from 100 watts in
Loss	Power remaining	From 100 W	On the air
0.5 dB	89 percent	89 W	Undetectable
1 dB	79 percent	79 W	Not audible
2 dB	63 percent	63 W	A third of an S unit
3 dB	50 percent	50 W	Half an S unit
6 dB	25 percent	25 W	One full S unit
10 dB	10 percent	10 W	Your 100 W station is a 10 W station
15 dB	3.2 percent	3.2 W	Two and a half S units
20 dB	1 percent	1 W	The feedline is the antenna

The number worth internalising is that loss applies in both directions. A run costing 6 dB makes you one S unit weaker at the far end and makes every incoming signal one S unit weaker at your receiver. On VHF and UHF weak-signal work that receive penalty is usually the one that hurts, and no amount of transmit power addresses it.

Reading the table for a decision

Total loss for typical runs, and the verdict
Run	Cable	Loss	Verdict
25 ft at 14 MHz	RG-58	0.45 dB	Entirely fine. Use cheap cable without guilt.
100 ft at 14 MHz	RG-58	1.8 dB	Acceptable. Better cable buys power handling, not decibels.
100 ft at 14 MHz	RG-213	0.8 dB	The right answer for a permanent HF run at any power.
50 ft at 146 MHz	RG-58	2.5 dB	Marginal. Nearly half your power gone before the antenna.
100 ft at 146 MHz	RG-58	5.0 dB	Bad. Two thirds of your power heating the cable.
100 ft at 146 MHz	LMR-400 class	1.5 dB	Correct. The 3.5 dB saving beats doubling transmitter power.
100 ft at 440 MHz	RG-58	10.5 dB	Unusable. Nine tenths of the power gone.
100 ft at 440 MHz	LMR-400 class	3.9 dB	Workable. Hardline is the answer for anything longer.

The single most useful line there is the 146 MHz comparison. Replacing 100 feet of RG-58 with Bolton400 low-loss coax, 100 ft with PL-259$119.95 saves 3.5 dB, which is more than doubling transmitter power, costs a fraction of an amplifier, and improves receive by the same amount. On any VHF or UHF run over about 25 feet it is the best value upgrade available.

Velocity factor, and when it matters

The velocity factor column is the speed of a signal in the cable as a fraction of the speed of light. It matters in exactly one situation: any time you need a specific electrical length, such as a quarter-wave matching stub, a half-wave measurement jumper, a phasing line between stacked antennas, or a coaxial stub filter.

Physical length is the free-space length multiplied by the velocity factor, so a quarter-wave stub for 14.175 MHz in solid polyethylene cable is 17.35 feet times 0.66, which is 11.45 feet. Using the free-space figure is the standard mistake and puts the stub about a third away from where you wanted it. Worked through on the impedance matching calculator.

For an ordinary feedline run velocity factor is irrelevant. The antenna does not care how many electrical wavelengths of cable sit between it and the radio, only how much attenuation.

Loss that is not in the datasheet

Every figure on this page assumes new cable in good condition, and three things degrade real installations without appearing in any table.

Water in the braid. The most common cause of a feedline that used to work. It enters through an unsealed connector, wicks along the braid, and raises loss steadily over months with no external sign. There is no repair. Seal every outdoor connection with Self-amalgamating rubber splicing tape$9.99 as the first layer, then Hand-moldable sealant tape$9.69 packed into the gap, then a vinyl outer wrap.
Ultraviolet damage. Non-UV-rated jackets crack within a few seasons of direct sun, which admits water. Buy black UV-stable jacket and dress the run with UV-resistant heavy duty zip ties, 100-pack$6.99 rather than natural-coloured ties, which themselves fail in one summer.
Bad connectors. A cold-soldered or badly crimped PL-259 can add several decibels, behave intermittently and change with temperature. This is the single most common fault found on an antenna analyser. Practise on scrap with a PL-259 solder connectors with reducers, 6-pack$9.99 before doing the run that matters.

All three are detectable with a NanoVNA H4 vector network analyzer$89.90, which shows loss and return loss across a sweep and will locate a bad connector along the cable by time-domain reflectometry in a couple of minutes.

The case for ladder line

Look at the ladder line row in the table above. It loses a small fraction of what any coax does, at every frequency, because almost all of its field is in air rather than in a plastic dielectric. That advantage is real and it is why a doublet fed with ladder line into a tuner remains a serious multiband antenna long after coax-fed compromises have been abandoned.

The costs are entirely practical. Ladder line must stay several inches clear of metal and of buildings, cannot be coiled, cannot be run casually through a wall, and needs either a balanced tuner or a balun at the shack end. It also picks up noise if routed badly. For a wire antenna fed at a high impedance on multiple bands it is unbeatable, and for a resonant monoband antenna it is more trouble than it is worth.

Buying advice in one paragraph

For a permanent HF run, buy MOOKEERF RG-213 coax, 100 ft with UHF male$115.99: it handles legal-limit power, tolerates being walked on and loses under a decibel at 20 metres. For short HF runs and portable work, JEFA Tech 240-series flex coax, 50 ft with PL-259$49.99 in RG-8X class saves weight and bulk at a modest penalty. For any VHF or UHF run over 25 feet, buy Bolton400 low-loss coax, 100 ft with PL-259$119.95 and stop thinking about it. For bench jumpers, Rydocyee RG-58 coax jumper, 25 ft$17.99 is fine and cheap. Buy the run in one piece where you can, not because connectors are lossy but because every joint is somewhere for water to get in. Full field on coax compared.

Common questions

Questions people ask about this

How much loss does 100 feet of coax have?

It depends entirely on the cable and the frequency. At 14 MHz, 100 feet of RG-58 loses 1.8 dB, RG-8X loses 1.2 dB, RG-213 loses 0.8 dB and LMR-400 class cable loses 0.7 dB. At 440 MHz the same runs lose 10.5, 8.0, 5.5 and 3.9 dB respectively. The ranking barely changes with frequency; the spread widens enormously.

Which coax should I buy for HF?

RG-213 for a permanent run, RG-8X for anything under about 50 feet or where flexibility matters. On HF the loss difference between good and mediocre cable over 100 feet is under a decibel, so the reasons to buy the better cable are power handling, weather survival and durability rather than decibels.

Which coax should I buy for VHF and UHF?

LMR-400 class or better for any run over about 25 feet, and hardline if the run is long and permanent. Above 50 MHz loss becomes the dominant consideration: 100 feet of RG-58 at 440 MHz throws away 91 percent of your transmitter power and attenuates every received signal by the same amount.

Is ladder line really almost lossless?

Yes, and by a wide margin. Open-wire and window line lose a small fraction of what coax does, because almost all the field is in air rather than in a dielectric. The costs are practical rather than electrical: it must stay clear of metal by several inches, cannot be coiled or run through a wall casually, and needs a balanced tuner or a balun at the shack end.

Does old coax get lossier?

Substantially, and the usual cause is water. Moisture wicks in through an unsealed connector and travels along the braid, raising loss steadily over months and years with no visible sign. Ultraviolet cracking of the jacket lets water in, which is why non-UV-rated cable fails in a few seasons. There is no repair; the run is replaced.

Do connectors add loss?

A properly made connector pair adds roughly 0.05 to 0.1 dB at HF and up to 0.2 dB at UHF, which is negligible against a hundred feet of cable. A badly made or corroded one is a different matter entirely and can add several decibels, behave intermittently and change with temperature. Connector count does not matter; connector quality does.

Keep going

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Disclaimer Researched guidance for planning purposes, not professional engineering, electrical or legal advice. Antenna work, RF exposure, mast and tower work, grounding and battery handling all carry real risk that depends on your specific site and installation. Verify anything safety-critical against current FCC rules, the National Electrical Code and the manufacturer's own documentation, and hire a professional where the job calls for one. We research equipment from published specifications, regulatory documents and verified owner reviews rather than claiming hands-on testing we have not done.