AWG Wire Gauge & Voltage Drop
Wire sizes, resistance and how much voltage your cable run will lose.
Size comparison
AWG chart
About this tool
How AWG works
American Wire Gauge numbers go down as wire gets thicker. Every 6 gauges halves the diameter, and every 3 gauges roughly halves the cross-section, so 12 AWG has about twice the copper of 15 AWG. Diameter = 0.127 mm × 92(36 − n)/39. Values here are for solid copper; stranded wire of the same gauge is slightly thicker overall.
Voltage drop
Current flows out and back, so the drop uses twice the cable length. For 12 V systems (cars, solar, LED strips) aim for 3% or less, which often needs much thicker wire than the current alone suggests.
Ampacity
The ampacity column is NEC Table 310.16 for copper building wire (not more than three current-carrying conductors, 30 °C ambient). For house wiring, breakers on 14, 12 and 10 AWG are limited to 15, 20 and 30 A. Chassis and bundle wiring follow different rules. Follow your local electrical code for mains work.