WireSizing
Wire gauge reference & calculator

What Wire Size for 100 Amps?

Copper Wire
1 AWG
7.3481 mm · 42.4077 mm²
Aluminum Wire
1/0 AWG
8.2515 mm · 53.4751 mm²
Breaker: 100A · Based on NEC Table 310.16 (75°C insulation)

Common Uses for 100A Circuits

Main panels, large sub-panels, service entrance

1 AWG Copper — Key Specs

Diameter7.3481 mm (0.289297")
Area42.4077 mm²
Resistance at 20°C0.4065 Ω/km
Weight379.973 kg/km
Ampacity (75°C)110 A

Important: For long wire runs, you may need to upsize the wire to compensate for voltage drop. NEC recommends keeping voltage drop under 3% for branch circuits. Use our voltage drop calculator to check.

Related

1 AWG full specifications → Full AWG chart → Wire size calculator → Ampacity tables →