AWG to mm² – Wire Gauge Conversion and Electrical Considerations
Understanding Wire Sizing Systems
The size of an electrical conductor is a critical factor in determining its performance, particularly in terms of current-carrying capacity and resistance. Wire sizing systems differ internationally, with the American Wire Gauge (AWG) used in the United States, while most other regions, including those following IEC 60228, classify conductors based on cross-sectional area in square millimetres (mm²). The AWG system is structured on a logarithmic scale, meaning that as the gauge number increases, the wire diameter decreases. This system is based on the number of drawing operations required to reduce a wire to its final size, with finer wires undergoing more passes through reducing dies. For example, a 10 AWG wire is significantly thicker than a 20 AWG wire, while the largest standard AWG size, 0000 (4/0), corresponds to approximately 107 mm² in metric terms. The scale extends down to extremely fine wires such as 40 AWG, which are commonly used in precision electronics and telecommunications applications.
From AWG to MCM – Measuring Larger Conductors
For wires that exceed 4/0 AWG, the measurement system shifts from gauge numbers to circular mils (CM). This unit of measurement defines the cross-sectional area of a conductor, where one circular mil represents the area of a circle with a diameter of one mil (1/1000 inch). When conductors reach significantly large sizes, they are expressed in MCM (or kcmil), which stands for thousands of circular mils. One MCM is equal to 1000 circular mils, making it a preferred unit for high-power electrical cables used in industrial, commercial, and utility-scale applications. In practical terms, 1 MCM is approximately 0.5067 mm², meaning that for quick estimations, a 2 MCM ≈ 1 mm² ratio can be used with a very small margin of error. MCM typically starts at 250 MCM.
Standard sizes are from 250 to 400 in increments of 50 kcmil, 400 to 1000 in increments of 100 kcmil, and from 1000 to 2000 in increments of 250 kcmil.
Large-scale electrical installations, such as power transmission systems, high-capacity feeders, and heavy-duty industrial equipment, often rely on MCM rather than AWG for specifying conductor size.
Standard kcmil wire sizes
| Area | Diameter | ||
| kcmil, MCM | mm2 | in | mm |
| 250 | 126.7 | 0.500 | 12.70 |
| 300 | 152.0 | 0.548 | 13.91 |
| 350 | 177.3 | 0.592 | 15.03 |
| 400 | 202.7 | 0.632 | 16.06 |
| 500 | 253.4 | 0.707 | 17.96 |
| 600 | 304.0 | 0.775 | 19.67 |
| 700 | 354.7 | 0.837 | 21.25 |
| 800 | 405.4 | 0.894 | 22.72 |
| 900 | 456.0 | 0.949 | 24.10 |
| 1000 | 506.7 | 1.000 | 25.40 |
| 1250 | 633.4 | 1.118 | 28.40 |
| 1500 | 760.1 | 1.225 | 31.11 |
| 1750 | 886.7 | 1.323 | 33.60 |
| 2000 | 1013.4 | 1.414 | 35.92 |
The Relationship Between AWG, Resistance, and Electrical Performance
Choosing the correct wire size involves more than just its physical dimensions; electrical resistance is a key factor that influences performance. Resistance dictates how much electrical energy is lost as heat and directly impacts efficiency. In general, a larger conductor (lower AWG number) has lower resistance, making it more suitable for carrying higher currents over longer distances with minimal voltage drop. Conversely, a smaller conductor (higher AWG number) has higher resistance, which limits the distance it can effectively transmit power without excessive losses. In alternating current (AC) applications, a phenomenon known as the skin effect comes into play, where higher-frequency signals cause the current to concentrate near the outer surface of the conductor. As frequency increases, the effective conducting area decreases, increasing resistance and reducing the efficiency of power transmission.
Selecting the Right Wire Size for Your Application
Several factors must be considered when selecting a wire size to ensure optimal performance and compliance with safety regulations. Current-carrying capacity (ampacity) is one of the most crucial considerations, as the conductor must be capable of handling the required current without overheating. Voltage drop is another key factor, particularly in long-distance wiring, where excessive resistance can result in significant power loss and reduced efficiency. Increasing the wire size can help mitigate voltage drop and improve overall system performance when a conductor is subject to extended runs. Environmental conditions also play a role, as factors such as temperature, insulation type, and installation method can influence how a conductor behaves under load. The application type is equally important, as different industries have specific wire size requirements depending on whether the conductor is used for power transmission, control signals, or data communication. In residential and commercial electrical installations, common conductor sizes typically range from 1 mm² to 6 mm², which correspond to approximately 16 AWG to 10 AWG.
AWG to mm² Conversion for International Compatibility
Since different regions use different measurement standards, having a reliable AWG to mm² conversion is essential for international compatibility. The primary measurement factor in IEC 60228 is based on the electrical resistance of the conductor rather than its physical dimensions alone. While AWG sizes can be converted directly to mm² using standard conversion tables, attention must also be given to conductor resistance to ensure compliance with IEC, NEC, and UL standards. At Tratos, electrical cables are available in both AWG and mm² specifications, ensuring compatibility across markets and compliance with multiple industry standards. Our conversion chart provides an easy reference for determining the equivalent metric size of an AWG conductor, making the selection process more straightforward for engineers, electricians, and designers working with international electrical systems.
AWG to mm conversion chart
| AWG | Diameter (Mm) | Diameter (Inch) | Area (Mm2) |
| 0000 (4/0) | 11.6840 | 0.4600 | 107.2193 |
| 000 (3/0) | 10.4049 | 0.4096 | 85.0288 |
| 00 (2/0) | 9.2658 | 0.3648 | 67.4309 |
| 0 (1/0) | 8.2515 | 0.3249 | 53.4751 |
| 1 | 7.3481 | 0.2893 | 42.4077 |
| 2 | 6.5437 | 0.2576 | 33.6308 |
| 3 | 5.8273 | 0.2294 | 26.6705 |
| 4 | 5.1894 | 0.2043 | 21.1506 |
| 5 | 4.6213 | 0.1819 | 16.7732 |
| 6 | 4.1154 | 0.1620 | 13.3018 |
| 7 | 3.6649 | 0.1443 | 10.5488 |
| 8 | 3.2636 | 0.1285 | 8.3656 |
| 9 | 2.9064 | 0.1144 | 6.6342 |
| 10 | 2.5882 | 0.1019 | 5.2612 |
| 11 | 2.3048 | 0.0907 | 4.1723 |
| 12 | 2.0525 | 0.0808 | 3.3088 |
| 13 | 1.8278 | 0.0720 | 2.6240 |
| 14 | 1.6277 | 0.0641 | 2.0809 |
| 15 | 1.4495 | 0.0571 | 1.6502 |
| 16 | 1.2908 | 0.0508 | 1.3087 |
| 17 | 1.1495 | 0.0453 | 1.0378 |
| 18 | 1.0237 | 0.0403 | 0.8230 |
| 19 | 0.9116 | 0.0359 | 0.6527 |
| 20 | 0.8118 | 0.0320 | 0.5176 |
| 21 | 0.7229 | 0.0285 | 0.4105 |
| 22 | 0.6438 | 0.0253 | 0.3255 |
| 23 | 0.5733 | 0.0226 | 0.2582 |
| 24 | 0.5106 | 0.0201 | 0.2047 |
| 25 | 0.4547 | 0.0179 | 0.1624 |
| 26 | 0.4049 | 0.0159 | 0.1288 |
| 27 | 0.3606 | 0.0142 | 0.1021 |
| 28 | 0.3211 | 0.0126 | 0.0810 |
| 29 | 0.2859 | 0.0113 | 0.0642 |
| 30 | 0.2546 | 0.0100 | 0.0509 |
| 31 | 0.2268 | 0.0089 | 0.0404 |
| 32 | 0.2019 | 0.0080 | 0.0320 |
| 33 | 0.1798 | 0.0071 | 0.0254 |
| 34 | 0.1601 | 0.0063 | 0.0201 |
| 35 | 0.1426 | 0.0056 | 0.0160 |
| 36 | 0.1270 | 0.0050 | 0.0127 |
| 37 | 0.1131 | 0.0045 | 0.0100 |
| 38 | 0.1007 | 0.0040 | 0.0080 |
| 39 | 0.0897 | 0.0035 | 0.0063 |
| 40 | 0.0799 | 0.0031 | 0.0050 |
