Wire (conductor) size is measured using the AWG (American Wire Gauge) system in the US, and the metric system uses mm (diameter) or mm² (cross-sectional area). A crucial point to understand is the inverse relationship between AWG and mm/mm². As the wire size increases, the AWG number decreases. Understanding how these two systems relate is a fundamental step for proper wire selection. The table below shows the corresponding diameter (mm) and cross-sectional area (mm²) for AWG values.
Generally preferred wire gauges for specific applications are:
- 20-26 AWG for analog signals.
- 18-24 AWG for instrumentation (low-power control).
- 10-16 AWG for speakers (audio power).
AWG to Metric System Conversion Chart - AWG to mm2
| AWG Gauge | Diameter (mm) | Area (mm²) |
|---|---|---|
| 000000 (6/0) | 14.73 | 170.30 |
| 00000 (5/0) | 13.12 | 135.10 |
| 0000 (4/0) | 11.68 | 107.16 |
| 000 (3/0) | 10.40 | 84.97 |
| 00 (2/0) | 9.27 | 67.40 |
| 0 (1/0) | 8.25 | 53.46 |
| 1 | 7.35 | 42.39 |
| 2 | 6.54 | 33.61 |
| 3 | 5.83 | 26.65 |
| 4 | 5.19 | 21.14 |
| 5 | 4.62 | 16.76 |
| 6 | 4.11 | 13.29 |
| 7 | 3.67 | 10.55 |
| 8 | 3.26 | 8.36 |
| 9 | 2.91 | 6.63 |
| 10 | 2.59 | 5.26 |
| 11 | 2.30 | 4.17 |
| 12 | 2.05 | 3.31 |
| 13 | 1.83 | 2.63 |
| 14 | 1.63 | 2.08 |
| 15 | 1.45 | 1.65 |
| 16 | 1.29 | 1.31 |
| 17 | 1.15 | 1.04 |
| 18 | 1.02 | 0.82 |
| 19 | 0.91 | 0.65 |
| 20 | 0.81 | 0.52 |
| 21 | 0.72 | 0.41 |
| 22 | 0.65 | 0.33 |
| 23 | 0.57 | 0.26 |
| 24 | 0.51 | 0.20 |
| 25 | 0.45 | 0.16 |
| 26 | 0.40 | 0.13 |
AWG Usage Guide and Approximate Metric Equivalents
The categories below demonstrate common usage trends. The actual selection must be determined by factors like current (A), voltage drop, temperature, insulation type, installation method, and compliance with standards (e.g., NEC, IEC).
| AWG Range / Example | Approximate Metric (mm²) | Typical Usage / Application Examples |
|---|---|---|
| 000000 (6/0 & larger) | 170 - 185 mm² | Main feeders carrying very high current, transformer and utility power distribution lines (major industrial mains). |
| 00000 - 0000 (5/0 - 4/0) | 107 - 150 mm² | Large generator / transformer connections, main distribution cables. |
| 000 - 00 (3/0 - 2/0) | 68 - 85 mm² | Main inputs for industrial panels, heavy-duty power cables. |
| 0 - 1 (1/0 - 1 AWG) | 42 - 53 mm² | Large motor feeds, solar inverter outputs, main UPS cables. |
| 2 - 3 | 26 - 34 mm² | Large motor / compressor feeds, short-distance high-current runs. |
| 4 - 6 | 13 - 21 mm² | Industrial power circuits, smaller motors, building main distribution (depending on local codes). |
| 7 - 9 | 8.4 - 10.6 mm² | Small motors, HVAC (air conditioning) feeds, specific lighting/receptacle circuits (per code). |
| 10 - 12 | 3.3 - 5.3 mm² | Residential/Commercial lighting circuits, lower-current protected receptacle (outlet) branches (varies by region/code). |
| 13 - 16 | 1.3 - 2.6 mm² | Low-power lighting, small appliance feeds, signal (not data/Ethernet) - solely power lines. |
| 17 - 20 | 0.5 - 1.04 mm² | Small power circuits, sensor feeds, low-power device wiring. |
| 21 - 24 | 0.2 - 0.5 mm² | Low Voltage: Signal cables, data, control (signal/communication), small speaker lines. |
| 25 - 26 | 0.12 - 0.16 mm² | Very fine signal wires, PCB connections, headphone / data lines (very low current). |
Conversion Formulas (AWG to Metric)
The following formula is used to calculate the diameter ($d) in millimeters from the AWG value:
From the diameter ($d$), the cross-sectional area ($A$) can be calculated as follows:
These formulas allow for the precise calculation of the metric equivalent from any AWG value.
Where Each System is Used
- AWG: Widely used in the United States, Canada, and some parts of Asia.
- Metric System (mm/mm²): Used in Europe, Turkey, and is the basis for most international standards (e.g., IEC, VDE, TSE).
Tips for Proper Wire Selection
- Always consider the current carrying capacity (ampacity) of the wire.
- Voltage drop increases with wire length, often necessitating a larger gauge (smaller AWG number or greater mm²) for long runs.
- The insulation type (PVC, XLPE, silicone, etc.) is critical depending on the application and environment.
- If tables or technical data are provided in AWG, always cross-reference the required metric equivalent for international projects.
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