American Wire gauge (AWG) chart and which Size to use

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AWG Wire Gauge Chart: Which Size Should You Use?

The wrong wire size gives you dim lights and sluggish motors at best, and a hot wire inside a wall at worst. Here is what AWG means, a quick chart, and a calculator to pick your size.

What is AWG?

AWG (American Wire Gauge) measures round, solid, non-ferrous wire. The counterintuitive part: the smaller the number, the thicker the wire. Every 6 gauge steps roughly halves the diameter; every 3 steps roughly halves the resistance.

d (mm) = 0.127 × 92^((36 − n) / 39)

For 12 AWG: 0.127 × 92^(24/39) ≈ 2.05 mm.

Quick-reference chart

AWG	Dia. (mm)	Ω / 1,000 ft	Max amps*	Common use
22	0.644	16.14	3	Signals, electronics
18	1.024	6.385	7	Lamp cords, low-voltage lighting
16	1.291	4.016	10	Extension cords, speakers
14	1.628	2.525	15	Household lighting
12	2.053	1.588	20	Outlets, garage circuits
10	2.588	0.999	30	Dryers, water heaters
8	3.264	0.628	40	Ranges, subpanels
6	4.115	0.395	55	Large appliances, feeders
4	5.189	0.249	70	EV chargers, big subpanels

*Copper, conservative 60 °C rating. Check your local code and insulation rating.

How to choose

Two things decide wire size: current and distance. The wire must carry the current safely (a 20 A breaker needs 12 AWG or thicker), and on long runs voltage drop matters:

V drop = 2 × L × I × R

L is the one-way length in feet, I is amps, and R is ohms per foot (chart value ÷ 1,000). Aim for under 3%. Low-voltage systems (12 V automotive, solar, RV) need much thicker wire than 120 V circuits carrying the same power.

Wire size calculator

Enter your circuit. Results update as you type.

System voltage (V) Current (A) One-way length (ft) Max voltage drop (%) ConductorCopperAluminum

AWG	Drop (V)	Drop (%)	Amps OK?	Drop OK?

Aluminum ampacity is derated 20%. This is a guide only; follow local electrical code.

Rules of thumb

• When in doubt, go one size thicker.
• Never use thinner wire than the breaker requires. The breaker protects the wire.
• Bundled wires, heat, and conduit reduce ampacity.
• Stranded wire suits cords and vehicles; solid suits walls.

For most home projects: 14 AWG for 15 A lighting, 12 AWG for 20 A outlets, 10 AWG for 30 A appliances. For anything inside walls or on a panel, follow local code or hire a licensed electrician.

learneaseguide.com · General information only; consult a licensed electrician.