What wire size do I need for 20 amps?

For a 20-amp circuit, use 12 AWG copper wire or 10 AWG aluminum wire. This is based on NEC Table 310.16 with 75°C rated insulation (THWN-2). Common uses: Kitchen, bathroom, garage circuits.

What Wire Size for 20 Amps?

Copper Wire

12 AWG

2.0525 mm · 3.3088 mm²

Aluminum Wire

10 AWG

2.5882 mm · 5.2612 mm²

Breaker: 20A · Based on NEC Table 310.16 (75°C insulation)

Common Uses for 20A Circuits

Kitchen, bathroom, garage circuits

12 AWG Copper — Key Specs

Diameter	2.0525 mm (0.080808")
Area	3.3088 mm²
Resistance at 20°C	5.2104 Ω/km
Weight	29.647 kg/km
Ampacity (75°C)	20 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.