# 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.

---

Source: https://vastcalc.com/calculators/conversion/wire-awg-to-mm
Category: Conversion
Last updated: 2026-04-08