Speaker Wire Calculator — Cable Gauge & Power Loss

For runs under 5m at 8 ohms: 16 AWG is fine. For 5-15m: 14 AWG. For 15-30m: 12 AWG. For longer runs or 4-ohm speakers, go one gauge thicker. Lower impedance speakers require thicker wire for the same loss percentage.

Keep power loss below 5% (about 0.45 dB). Below 2% (about 0.18 dB) is ideal. The dB figure is a voltage ratio — 20 × log10(Z / (Z + R_cable)) — so 5% maps to roughly 0.45 dB, not 0.2 dB. Losses above 10% become audible and waste amplifier power as heat in the cable. For professional installations, aim for under 0.5 dB loss.

Cable resistance is the primary factor — it reduces damping factor and causes minor frequency response changes. For short runs with adequate gauge, the effect is negligible. Exotic cable materials and constructions offer no measurable benefit beyond achieving low resistance.

Cable resistance forms a voltage divider with speaker impedance. A 0.5Ω cable with an 8Ω speaker loses 6% of power. The same cable with a 4Ω speaker loses 11%. Lower impedance speakers always need thicker cables for the same loss percentage.