# AWG to mm Calculator

Convert AWG wire gauge to diameter in mm and inches, cross-section area in mm2 and circular mils, plus copper resistance per 1000 feet.

## What this calculates

Convert any American Wire Gauge number to diameter in millimeters and inches, cross-sectional area, and resistance for copper wire. AWG is the standard wire sizing system used in North America for electrical conductors.

## Inputs

- **AWG Number** — min 0, max 40 — Enter the AWG wire gauge (0 to 40). Lower numbers = thicker wire.

## Outputs

- **Diameter (mm)** (mm) — Wire diameter in millimeters.
- **Diameter (inches)** (in) — Wire diameter in inches.
- **Cross-Section Area** (mm²) — Cross-sectional area in square millimeters.
- **Circular Mils** (cmil) — Cross-sectional area in circular mils.
- **Resistance (Copper)** (Ω/1000ft) — Resistance per 1000 feet of copper wire at 20°C.
- **Max Ampacity (Chassis)** — formatted as text — Approximate maximum current for chassis wiring.

## Details

American Wire Gauge (AWG) is a standardized system for wire sizing. Smaller AWG numbers mean thicker wire. Each step of 6 AWG doubles the wire diameter, and each step of 3 AWG doubles the cross-sectional area.

Formula: d(mm) = 0.127 x 92^((36 - AWG) / 39)

Common AWG Sizes

AWG
Diameter (mm)
Area (mm2)
Resistance (ohm/1000ft)
Typical Use

4
5.189
21.15
0.249
Service entrance

8
3.264
8.37
0.628
Range/dryer circuits

10
2.588
5.26
0.999
30A circuits

12
2.053
3.31
1.588
20A household circuits

14
1.628
2.08
2.525
15A household circuits

16
1.291
1.31
4.016
Extension cords

18
1.024
0.82
6.385
Lamp cords, low-voltage

22
0.644
0.33
16.14
Electronics, data

AWG vs metric: The rest of the world uses metric wire sizes measured directly in mm2 cross-section. Converting between AWG and mm2 is one of the most common tasks when working with international electrical standards.

## Frequently Asked Questions

**Q: What does AWG stand for?**

A: AWG stands for American Wire Gauge. It's a standardized wire sizing system used primarily in North America. The gauge number indicates the number of drawing operations used to produce a given wire diameter -- historically, higher numbers meant more draws and thinner wire.

**Q: Why do smaller AWG numbers mean thicker wire?**

A: The AWG system is based on the number of times wire was drawn through progressively smaller dies during manufacturing. More drawing steps (higher gauge number) produced thinner wire. AWG 0 (1/0) is about 8.25 mm diameter, while AWG 40 is only 0.08 mm.

**Q: What AWG do I need for a 20-amp circuit?**

A: For a standard 20-amp residential circuit, the National Electrical Code requires a minimum of 12 AWG copper wire. For a 15-amp circuit, 14 AWG is the minimum. Always follow your local electrical code, which may have stricter requirements.

**Q: How does AWG relate to metric wire sizes?**

A: Metric wire is specified by cross-sectional area in mm2, not by gauge number. There's no exact one-to-one match. For example, 12 AWG (3.31 mm2) is close to the metric 3.5 mm2 size, and 14 AWG (2.08 mm2) is close to the metric 2.5 mm2 size.

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Source: https://vastcalc.com/calculators/conversion/wire-awg-to-mm
Category: Conversion
Last updated: 2026-04-21