How much resistance your speaker cables add, how much that kills your amp's damping factor, and how many dB of signal you actually lose. Pick a gauge and length - the cross-section shows the conductor at true scale next to a reference AWG 16.
My setups
Save cable + speaker + amp combinations. Useful when comparing gauges or planning long in-wall runs.
Signal loss-Across the cable, into your speaker load.
System damping-Amp damping factor after cable resistance.
Cross-section view, drawn to scale. The bigger circle is the bigger conductor. Material colour matches the real-world appearance: copper = warm, silver = cool, aluminium = grey.
Your pickAWG 16 · copperReferenceAWG 16 · copper
Both circles share the same scale: 23x life-size. The "your pick" diameter is real-world x the same scale factor as the reference - so the size comparison is honest, not zoomed differently.
Show the math
The formulas, plain-English
Cable resistance and signal loss
Resistance is ρ x (length x 2) ÷ cross-section. Copper at AWG 16 over 5 m is 0.131 Ω round-trip. The voltage divider against speaker impedance gives the loss: dB = 20·log10(Z ÷ (Z + R_cable)).
Below -0.5 dB is generally inaudible; below -0.1 dB is bulletproof. Halve the length and you halve the resistance; double the cross-section (3 AWG steps down) and you halve it too.
System damping factor
DF_sys = Z ÷ (Z_amp + R_cable) where the amp's output impedance is the rated DF rolled back: Z_amp = Z ÷ DF_amp. Cable resistance is in series with the amp, so it directly degrades damping.
Damping controls how well the amp grips bass transients. Below 20 you lose grip on woofers; below 10 the bass becomes audibly loose. A high-DF amp (500+) gives you generous headroom against cable degradation.
AWG gauge, by recommended max length
Max one-way length to keep loss under -0.1 dB into an 8 Ω load. For 4 Ω, halve every length. Every 3 AWG steps down doubles the cross-section.
Gauge
Cross-section
8 Ω max length
Notes
AWG 24
0.21 mm²
~1.5 m
Wall-wart cable. Not for speakers.
AWG 22
0.33 mm²
~2.5 m
Lamp cord. Marginal for desk monitors.
AWG 20
0.52 mm²
~4 m
Bedroom-system minimum.
AWG 18
0.82 mm²
~6 m
Common minimum for full-room hi-fi.
AWG 16
1.31 mm²
~10 m
Standard home audio gauge. Solid pick.
AWG 14
2.08 mm²
~16 m
Long runs. 4 Ω-friendly.
AWG 12
3.31 mm²
~25 m
Whole-house, in-wall, low-Z loads.
AWG 10
5.26 mm²
~40 m
Pro / install. Diminishing returns at home.
FAQ
Speaker cable FAQ.
Whether gauge actually matters, how damping factor changes with cable length, and when expensive audiophile cable is and is not worth the money.
Does speaker cable gauge actually matter?
Yes, but only past a threshold. Below 16 AWG on long runs (>15 ft), resistance becomes a noticeable fraction of the speaker impedance and bass control suffers. Above 14 AWG you are well into diminishing returns. The calculator shows exactly how much resistance and damping factor you lose for any gauge and length.
What is amplifier damping factor and why does it matter?
Damping factor is the speaker impedance divided by the amplifier output impedance plus cable resistance. Higher damping factor means tighter bass control: the amp can stop the woofer from ringing. Cable resistance is part of the total impedance, so thin cables on long runs reduce system damping factor below the spec.
How long can speaker cables be before signal loss?
For 12 AWG cable to 8 ohm speakers, run length up to 50 feet adds less than 0.4 dB attenuation, which is inaudible. For 16 AWG at 4 ohm speakers, 25 feet is the practical limit before bass control degrades. The calculator outputs both the dB loss and the damping factor change so you can decide.
Are expensive speaker cables worth it?
For their copper alone, no. Plain OFC or 4N copper at the right gauge is electrically identical to anything more expensive in the audible band. What you can pay for is build quality, connector reliability, and shielding for noisy environments. The calculator only cares about resistance.
