Speaker wire gauge: length, resistance and connections

Start with the complete route

This guide concerns the cable between an amplifier's speaker output and a passive speaker. It does not cover mains wiring or ordinary line-level interconnects. Confirm the system type in active, powered and passive speakers before treating an unfamiliar connection as a speaker output.

Measure the one-way route, including practical slack and bends. Then check the amplifier and speaker manuals for supported cable sizes and termination types. The cable must suit the route and fit both ends securely.

Gauge describes the conductor

American Wire Gauge, or AWG, is a conductor-size system: a lower AWG number means a thicker conductor. SVS's gauge explanation connects selection with run length and speaker impedance. The thickness of the outer jacket does not establish the conductor size inside it.

Also check conductor material and the cable's published resistance. A size label is not a measured resistance for every product. Longer conductors add more series resistance, and that resistance becomes more significant relative to a lower speaker load. A speaker's real impedance also changes with frequency, so its nominal rating is only part of the description.

A calculated example, with its assumptions

The Belden 5000UE data sheet, revision dated 20 February 2026, lists two 12 AWG bare-copper conductors and nominal conductor resistance of 1.6 Ω per 1,000 ft. This identifies the example cable; it is not a recommendation that every system needs 12 AWG.

Converted to metres, that is about 0.005249 Ω/m per conductor. The circuit includes the outgoing and return conductors, so calculate the loop using both:

Loop resistance = 2 × one-way length × resistance per metre.

For an ideal source and a purely resistive load, the voltage fraction reaching the load is load resistance ÷ (load resistance + loop resistance). Converting that fraction to decibels gives these calculated changes:

• 5 m one way: 0.05249 Ω loop resistance; about −0.11 dB into 4 Ω or −0.06 dB into 8 Ω.
• 10 m one way: 0.10499 Ω loop resistance; about −0.23 dB into 4 Ω or −0.11 dB into 8 Ω.

This simplified calculation assumes zero amplifier output resistance, no connector loss, no reactive effects and no temperature change. It uses resistors in place of real speakers. The figures illustrate length and load dependence; they are neither measurements of an installed cable nor claims that a particular difference will be audible.

Build a selection note

• Route: one-way length, slack and how the cable will be supported.
• Cable: conductor material, size and data-sheet resistance, keeping conductor and loop values distinct.
• Load: speaker impedance information and the amplifier's supported arrangement.
• Ends: permitted wire or plug size, connector type, polarity markings and strain relief.
• Condition: intact insulation and secure, undamaged connections.

Use the relevant manufacturer's length/gauge guidance with its stated assumptions. Price, jacket size or a premium material label does not by itself establish a listening improvement. Hidden or in-wall installation needs a suitable cable and installation requirements beyond this guide.

Connect without loose strands or polarity mistakes

Power down and unplug equipment as its manuals require before working on speaker connections. The Denon PMA-600NE connection instructions, for example, require unplugging and warn against protruding conductors and shorts.

Prepare only the exposed length specified for the actual terminal. Preserve left/right channels and the indicated positive/negative connections; secure each termination and inspect for strands that could bridge terminals or touch the chassis. Do not cut away strands just to force oversized wire into an unsuitable connector.

Do not join speaker return terminals together or assume they are ground. The NAD C 268 manual, printed page 5, gives an explicit counterexample with terminals that must not be joined or grounded. After the connections pass the manual's checks, restore power with a low initial volume.