What AWG is household wiring?

US household 15 A circuits use AWG 14 (minimum). 20 A circuits require AWG 12. Dryer and oven circuits at 30–50 A use AWG 10 or AWG 8.

Does stranded vs solid wire affect ampacity?

For the same AWG, solid and stranded wire have nearly identical DC resistance and ampacity. Stranded wire is more flexible and better for moveable connections.

Wire Gauge Ampacity Calculator (AWG)

Find the ampacity (current-carrying capacity) and resistance of copper wire by AWG gauge. Covers AWG 28 (thin signal wire) to AWG 0000 (heavy power cable).

By AbraCalc Editorial Team · Reviewed by AbraCalc Methodology Review · Last reviewed: 2026-06-25

Embed this tool on your site

<iframe src="https://abracalc.com/calculator/wire-gauge-ampacity/embed.html" width="340" height="320" style="border:1px solid #e4e7ec;border-radius:12px" loading="lazy"></iframe>

How to use this tool

Enter awg gauge in the fields above.
Results update instantly as you type — or click Calculate.
Read your ampacity (nec chassis wiring) and the full breakdown beneath it.

The American Wire Gauge (AWG) system assigns lower numbers to thicker wires. Thicker wire carries more current (higher ampacity) and has lower resistance per metre. The NEC ampacity values shown are for copper conductors with 60 °C insulation in free air (chassis wiring). Conduit-bundled or wall-run cables require further derating per NEC 310-15.

Formula

Ampacity is read from the NEC 310-16 lookup table for the given AWG gauge.

Conductor diameter: d (mm) = √(area_mil) × 0.02540

DC resistance: R (Ω/km) = ρ × 1000 / A, where ρ = 1.724 × 10⁻⁸ Ω·m and A (m²) = area_mil × 5.067 × 10⁻¹⁰

How it works

This tool looks up the NEC 310-16 chassis-wiring ampacity for copper conductors with 60 °C insulation, then derives the conductor diameter from the circular-mil area using the inch-to-mm conversion factor, and computes DC resistance from copper's standard resistivity (1.724 × 10⁻⁸ Ω·m) divided by the cross-sectional area in m².

Results apply to single conductors in free air under the stated insulation temperature rating. Bundled-cable derating, ambient temperature corrections, and AC skin-effect losses are not included.

Worked example

Worked example — AWG 14

AWG 14 has a circular-mil area of 4110 cmil (from the NEC table).
NEC 310-16 chassis ampacity for AWG 14 copper at 60 °C insulation = 15 A.
Conductor diameter = √4110 × 0.02540 = 64.109 × 0.02540 ≈ 1.628 mm.
DC resistance: A = 4110 × 5.067 × 10⁻¹⁰ = 2.083 × 10⁻⁶ m²; R/km = (1.724 × 10⁻⁸ / 2.083 × 10⁻⁶) × 1000 ≈ 8.276 Ω/km.

Ampacity = 15 A; diameter ≈ 1.628 mm; DC resistance ≈ 8.276 Ω/km.

Key terms

AWG (American Wire Gauge): A standardised US wire-size system where larger AWG numbers indicate thinner wires; AWG 28 is a fine signal wire, AWG 0000 (4/0) is a heavy power cable.
Ampacity: The maximum continuous current a conductor can carry safely without exceeding its temperature rating, expressed in amperes.
Circular mil (cmil): A unit of cross-sectional area equal to the area of a circle with a diameter of one thousandth of an inch (1 mil); used to describe wire cross-sections in the AWG system.
NEC 310-16: A table in the US National Electrical Code listing allowable ampacities for insulated conductors under defined conditions of installation.
DC resistance: The opposition a conductor offers to direct current, determined by its resistivity, length, and cross-sectional area; ignores frequency-dependent skin-effect losses.

Frequently asked questions

What AWG is household wiring?: US household 15 A circuits use AWG 14 (minimum). 20 A circuits require AWG 12. Dryer and oven circuits at 30–50 A use AWG 10 or AWG 8.
Does stranded vs solid wire affect ampacity?: For the same AWG, solid and stranded wire have nearly identical DC resistance and ampacity. Stranded wire is more flexible and better for moveable connections.