Speaker Wire Gauge Chart: Resistance Against Impedance
Quick answer / TL;DR: Short answer: use 16 AWG for runs up to about 10 metres with 8 ohm speakers, 14 AWG up to about 15 metres, and 12 AWG beyond that or for 4 ohm speakers. Remember that both conductors count, so the loop resistance is twice the one-way figure. Below about 5 metres with 8 ohm speakers, differences between 16 and 12 AWG are not audible. Copper matters more than oxygen-free marketing, and copper-clad aluminium should be avoided.
Four gauges, four distances: the conductor size follows the run.Speaker cable carries current into a low impedance load, so its resistance matters as a proportion of that load. A run that adds half an ohm to an 8 ohm speaker is a small effect; the same half ohm against a 4 ohm speaker is twice as significant.
The practical rule is to keep total cable resistance under about five percent of the speaker impedance. The chart below converts that into lengths for the common gauges.
The Resistance Table
Resistance per 1000 feet is the standard figure quoted for wire, and the loop resistance for a run is twice the one-way value.
| AWG | Ohms per 1000 ft | Ohms per 100 m | Loop at 10 m | Loop at 20 m |
|---|
| 16 | 4.02 | 13.2 | 0.26 ohm | 0.53 ohm | 14 | 2.53 | 8.3 | 0.17 ohm | 0.33 ohm | 12 | 1.59 | 5.2 | 0.10 ohm | 0.21 ohm | 10 | 1.00 | 3.3 | 0.07 ohm | 0.13 ohm |
Applying the five percent rule: with an 8 ohm speaker, 0.4 ohm is the limit, which 16 AWG reaches at roughly 15 metres one way. With a 4 ohm speaker the limit is 0.2 ohm, which halves every distance.
The Practical Chart
The same figures expressed as usable length avoid the arithmetic at the point of purchase.
| Speaker impedance | 16 AWG | 14 AWG | 12 AWG |
|---|
| 8 ohm | up to 15 m | up to 24 m | up to 38 m | 4 ohm | up to 7 m | up to 12 m | up to 19 m | 2 ohm | up to 4 m | up to 6 m | up to 9 m |
What Else Matters
Gauge dominates, but two other factors are worth checking before buying.
- Conductor material: copper is the baseline, copper-clad aluminium has higher resistance
- Strand count: more strands flex better but do not change resistance significantly
- Termination: a loose connection adds more resistance than a gauge step
- Damping factor: very low impedance speakers benefit most from heavier cable
Real-World Applications
Domestic stereo, 3 metre runs
16 AWG is entirely adequate with 8 ohm speakers. The resistance is a small fraction of an ohm, and heavier cable makes no audible difference at that distance.
Home cinema with 12 metre rear runs
14 AWG with 8 ohm speakers, or 12 AWG if the surrounds are 4 ohm. Rear runs are the case where gauge actually matters in domestic installations.
In-wall installation
Use cable rated for in-wall use, typically with a CL rating, and choose one gauge heavier than the calculation suggests, because the cable cannot be replaced easily.
Where heavy gauge is wasted
Short runs with 8 ohm speakers. Paying for 10 AWG over 3 metres buys a change far below audibility, and the money is better spent on termination quality.
Related reading: Speaker cable connectors — blogs/news/speaker-cable-connectors
Related reading: Choosing speaker cable length — blogs/news/speaker-cable-length
Standards and Verification
Speaker cable is covered by electrical practice and by the wire gauge tables maintained by standards bodies such as ASTM, which publish resistance and current capacity for each AWG size. There is no audio-specific standard for speaker cable construction.
Verify by measuring resistance with a meter across both conductors at one end with the far end shorted, which gives the loop resistance directly. That is more reliable than trusting a printed specification.
For long runs, compare the result against five percent of the speaker's nominal impedance. A figure above that explains dull or loose bass, which is the audible effect of series resistance.
Do not use mains cable as speaker cable. It works electrically, but the insulation colours invite confusion, and the practice makes later fault-finding ambiguous in a way that is easily avoided with proper cable.
Frequently Asked Questions
What gauge speaker wire should I use?
16 AWG for short runs with 8 ohm speakers, 14 AWG up to about 15 metres, and 12 AWG for longer runs or 4 ohm speakers.
Does thicker speaker cable sound better?
Only when the thinner cable's resistance is a significant fraction of the speaker impedance. On short runs the difference is not audible.
Does oxygen-free copper matter?
Less than the marketing suggests. Avoiding copper-clad aluminium matters much more, because its resistance is significantly higher.
Is loop resistance double the one-way figure?
Yes. The current travels out and back, so both conductors add resistance in series with the speaker.
What about bi-wiring?
It uses two runs per speaker. The electrical effect is small, and heavier single cable achieves most of what bi-wiring offers.
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