Wire gauge & voltage drop

What gauge to run, and what you'll lose over the distance — the two questions that actually decide a wiring job.

18 AWG

rated for 10 A — comfortably carries 10 A

Diameter: 1.02 mm
Cross-section: 0.823 mm²
Round-trip resistance: 0.085 Ω
Voltage drop: 0.850 V
Drop as % of supply: 7.1%

Over 5% drop — go up a gauge or shorten the run.

Current (A)One-way run length (m)Supply voltage (V)Wire gauge

Ampacity figures are a conservative rule of thumb for single insulated copper conductors in free air — a general reference for low-voltage projects, not a substitute for your local electrical code. For mains or building wiring, follow the code and use a licensed electrician.