A speaker wire gauge chart matches the wire's cross-section to the length of the run: 18 AWG typically serves short bookshelf runs, 16 AWG covers most living-room distances, and 14 or 12 AWG takes long runs and low-impedance speakers. ASTM B258 prescribes the standard nominal diameters and cross-sectional areas behind the numbers, and Remington's AWG chart lists 18 AWG at 0.0403 inches (0.823 mm2) and 6.385 ohms per 1,000 feet, stepping down to 10 AWG at 0.1019 inches (5.26 mm2) and 0.9989 ohms. In walls the run needs a CL2 or CL3 listing; on boats, tinned copper; outdoors, a jacket rated for the exposure.
Figures on this page were checked October 2026. Every table row carries its source and access date.
The speaker wire gauge chart
This speaker wire gauge chart collects the conductor numbers behind the spools: diameter, cross-sectional area and resistance for the 10 through 18 AWG sizes that speaker runs actually use, and then the three environments that change the jacket decision, outdoors, on a boat and inside the wall. ASTM B258 is the standard that prescribes the nominal diameters and cross-sectional areas of AWG solid round wires used as electrical conductors, along with the rules for calculating their resistances.
| AWG | Diameter (in) | Diameter (mm) | Area | DC resistance per 1,000 ft | Source / as of |
|---|---|---|---|---|---|
| 18 | 0.0403 | 1.024 | 1.624 kcmil (0.823 mm2) | 6.385 ohms | Remington AWG chart, 2026-10-13 |
| 16 | 0.0508 | 1.290 | 2.585 kcmil (1.31 mm2) | 4.016 ohms | Remington AWG chart, 2026-10-13 |
| 14 | 0.0641 | 1.628 | 4.105 kcmil (2.08 mm2) | 2.525 ohms | Remington AWG chart, 2026-10-13 |
| 12 | 0.0808 | 2.052 | 6.532 kcmil (3.31 mm2) | 1.588 ohms | Remington AWG chart, 2026-10-13 |
| 10 | 0.1019 | 2.588 | 10.38 kcmil (5.26 mm2) | 0.9989 ohms | Remington AWG chart, 2026-10-13 |
The values are nominal, as the chart itself notes. Remington prints them for solid copper, and stranded speaker constructions land close but not identical, so treat the table as the reference frame for the gauge system instead of a laboratory sheet for any one spool. Resistance is the column that matters for sound: it sits in series with the speaker, and it counts twice, once for each conductor in the out-and-back loop.
Choosing a gauge
The resistance column explains the usual advice. A longer run puts more of that series resistance between amplifier and driver, and lower-impedance speakers draw more current through the same wire, so long runs and 4-ohm home speakers pull the choice toward the thicker end of the chart while short runs tolerate the thinner end. A practical check is the loop sum: run length doubled, times resistance per foot, gives the wire's contribution, and keeping that contribution small next to the speaker's impedance is the goal. On the commercial side, the 70V distributed systems playbook shows the other answer to the same problem, raising the voltage on the line so the same power needs less current. Wiring discipline is simple: the two conductors carry the same signal, so keep positive on positive and negative on negative from amplifier to speaker, because a swapped pair at one speaker puts it out of phase with the rest.
Outdoor runs
Sunlight and weathering are what outdoor jacket ratings exist for: a cable left in the open ages at its jacket first, and the jacket is the first line the environment attacks. Cables sold for burying carry the rating in the print legend, marked for direct burial, and the legend is the manufacturer's statement of where the construction belongs. When the outdoor run re-enters the building to reach an amplifier, the portion inside becomes structural wiring again, and the in-wall rules below take over from there.
Marine runs: tinned copper
On a boat the environment reaches the metal itself. Salt air and damp find every exposed strand and terminal, and the corrosion that forms on bare copper builds resistance at exactly the joints carrying current. The marine industry's answer is tin plating over the copper. Ancor, a marine wire maker, has built tinned copper Marine Grade wire for over forty years and states that its products are designed to meet UL, ABYC, NMMA and USCG standards. ABYC, the American Boat and Yacht Council, maintains the standards program the marine industry builds to, so a marine marking on a spool points back to a written standard.
In-wall ratings: CL2 and CL3
Inside the wall, the wire becomes part of the building, and the National Electrical Code, published by the National Fire Protection Association, takes an interest. Blue Jeans Cable's NEC guide traces the jurisdiction: audio interconnect cables and speaker wires fall under NEC Article 640, which hands specific installation settings to Article 725, the article covering remote-control, signaling and power-limited circuits.
| Marking | What it means | Where it may go (per the guide) | Source / as of |
|---|---|---|---|
| CL2 / CL3 | The standard in-wall speaker listings | Always permitted in wall | Blue Jeans Cable NEC guide, 2026-10-13 |
| CL2X / CL3X | Residential-suffix grades, a step below plain CL2 | Raceways; or without a raceway, one and two family dwellings when under 1/4 inch in diameter | Blue Jeans Cable NEC guide, 2026-10-13 |
| CL2R / CL3R | Riser grades | Commercial or multifamily vertical runs crossing more than one floor | Blue Jeans Cable NEC guide, 2026-10-13 |
| CL2P / CL3P | Plenum grades | Air-handling plenum spaces, where CMP is also a permitted substitute | Blue Jeans Cable NEC guide, 2026-10-13 |
The guide adds one more simplification: the NEC allows a higher rating to substitute for a lower one, and it lists CM, CMP, CMR, CMG, CL2R, CL3R, CL2P, CL3P and PLTC as usable where a lesser rating applies. Local rules still get the final word, which the guide says outright: installations that need a permit answer to the local code office.
The wireless hop happens upstream
None of the three environments changes the wireless path, because Bluetooth does not replace speaker wire: the run from amplifier to speaker stays copper. What goes wireless is the source feeding the amplifier. A Bluetooth receiver with line-level outputs takes the stream and hands the amplifier its input the way a CD player would, and every decision on this page applies downstream, unchanged. The speaker selector reference covers what happens when one amplifier feeds several pairs, and the connector reference hub indexes the input-side plugs. The receiver below is the upstream piece for a living-room system.
FAQ
Read the resistance column against the length of your run. A short run to bookshelf speakers tolerates 18 AWG, most living-room distances land comfortably on 16 AWG, and long runs, or runs feeding 4-ohm speakers, move to 14 or 12 AWG where the chart shows less resistance per foot. The speaker wire gauge chart above gives the exact nominal values, and the loop calculation, run length doubled for the out-and-back path, times resistance per foot, tells you how much resistance the wire adds in series with the speaker.
Inside a wall the wire becomes part of the building, and the National Electrical Code governs it. Blue Jeans Cable's NEC guide traces the path: audio and speaker wire fall under NEC Article 640, which hands specific installation settings to Article 725, and under that article CL2 and CL3 are always permitted in wall. The residential-suffix grades CL2X and CL3X are a step below plain CL2. Permit rules vary by jurisdiction, so the guide's advice is to check with the local permitting office when a project needs a permit.
Salt air and damp reach exposed copper at every strand and terminal, and the corrosion products that form raise resistance where the current has to pass. Tin plating slows that attack, which is why marine wire makers build with tinned copper. Ancor, a marine wire maker, has produced tinned copper Marine Grade wire for over forty years and states that its products are designed to meet UL, ABYC, NMMA and USCG standards, so a spool marked for marine use points at a written rulebook rather than a marketing word.
Yes, with the jacket matched to the exposure. Cables sold for burying say so in the print legend, marked for direct burial, and that legend is the manufacturer's rating, so read it rather than judging by color or feel. Where the run re-enters the building to reach an amplifier, the in-wall rules take over again for the portion inside. The wireless alternative is to leave the runs as they are and make the source wireless instead, which a Bluetooth receiver at the amplifier does in one step.
blafili R1 Bluetooth Receiver
The speaker runs stay copper; the source goes wireless. R1 puts out on RCA into the amplifier that this wire serves, and the whole gauge decision on this page applies downstream, unchanged.
- ASTM, ASTM B258-18 (R2026), "Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors": "This specification prescribes standard nominal diameters and cross-sectional areas of American Wire Gage (AWG) sizes of solid round wires" used as electrical conductors, and provides equations and rules for calculating nominal mass, lengths and resistances. store.astm.org/b0258-18r26.html, accessed 2026-10-13
- Remington Industries, "Magnet Wire Gauge Chart": AWG 18: 0.0403 in / 1.024 mm diameter, 1.624 kcmil (0.823 mm2), 6.385 ohms per 1,000 ft; AWG 16: 0.0508 / 1.290, 2.585 kcmil (1.31 mm2), 4.016 ohms; AWG 14: 0.0641 / 1.628, 4.105 kcmil (2.08 mm2), 2.525 ohms; AWG 12: 0.0808 / 2.052, 6.532 kcmil (3.31 mm2), 1.588 ohms; AWG 10: 0.1019 / 2.588, 10.38 kcmil (5.26 mm2), 0.9989 ohms; the page notes "all values are nominal unless otherwise specified". remingtonindustries.com/resources/magnet-wire/, accessed 2026-10-13
- Blue Jeans Cable, "Understanding In-wall Speaker, Video and Audio Cable Ratings": audio interconnect cables and speaker wires fall under NEC Article 640 and, per 640.21(C), under Article 725; "(1) CL2 and CL3 are always permitted"; "(2) CL2X ('X' is a residential suffix, signifying a lower grade than plain CL2) or CL3X may be installed in raceways"; CL2X or CL3X under 1/4 inch in diameter may go in 1 or 2 family dwellings without a raceway; in plenums "CL2P or CL3P are required, and CMP is a permitted substitution"; commercial risers crossing more than one floor require "CL2R or CL3R"; "The NEC allows cable of a higher rating to be substituted for a lower rating", listing CM, CMP, CMR, CMG, CL2R, CL3R, CL2P, CL3P and PLTC. bluejeanscable.com/articles/inwallrating.htm, accessed 2026-10-13
- NFPA, "NFPA 70 (NEC) Code Development" page: the National Electrical Code is developed and maintained by the National Fire Protection Association. nfpa.org/codes-and-standards/nfpa-70-standard-development/70, accessed 2026-10-13
- Ancor brand page on Navico: "For over 40 years, Ancor has been the industry leader for high-quality tinned copper Marine Grade® wire and cable" and "Ancor products are manufactured to precise specifications and designed to meet UL, ABYC, NMMA, and USCG standards." www.navico.com/ancor, accessed 2026-10-13
- ABYC, "Standards" page: The American Boat and Yacht Council maintains its standards program and standards library for the marine industry at this page. abycinc.org/standards, accessed 2026-10-13