AWG and kcmil to mm² conversion with diameter, resistance and weight, NEC Table 310.16 ampacities, and metric cable sizes with their nearest AWG.
| Size | Diameter (mm) | Diameter (in) | Area (mm²) | Ω/km Cu | Ω/km Al | Cu weight (kg/km) |
|---|---|---|---|---|---|---|
| 600 kcmil | 19.675 | 0.7746 | 304.02 | 0.0567 | 0.0930 | 2,702.8 |
| 500 kcmil | 17.961 | 0.7071 | 253.35 | 0.0681 | 0.1116 | 2,252.3 |
| 400 kcmil | 16.064 | 0.6325 | 202.68 | 0.0851 | 0.1394 | 1,801.9 |
| 350 kcmil | 15.027 | 0.5916 | 177.35 | 0.0972 | 0.1594 | 1,576.6 |
| 300 kcmil | 13.912 | 0.5477 | 152.01 | 0.1134 | 0.1859 | 1,351.4 |
| 250 kcmil | 12.700 | 0.5000 | 126.68 | 0.1361 | 0.2231 | 1,126.2 |
| 4/0 AWG | 11.684 | 0.4600 | 107.22 | 0.1608 | 0.2636 | 953.2 |
| 3/0 AWG | 10.405 | 0.4096 | 85.03 | 0.2028 | 0.3324 | 755.9 |
| 2/0 AWG | 9.266 | 0.3648 | 67.43 | 0.2557 | 0.4192 | 599.5 |
| 1/0 AWG | 8.251 | 0.3249 | 53.48 | 0.3224 | 0.5285 | 475.4 |
| 1 AWG | 7.348 | 0.2893 | 42.41 | 0.4066 | 0.6665 | 377.0 |
| 2 AWG | 6.544 | 0.2576 | 33.63 | 0.5127 | 0.8404 | 299.0 |
| 3 AWG | 5.827 | 0.2294 | 26.67 | 0.6464 | 1.060 | 237.1 |
| 4 AWG | 5.189 | 0.2043 | 21.15 | 0.8152 | 1.336 | 188.0 |
| 6 AWG | 4.115 | 0.1620 | 13.30 | 1.296 | 2.125 | 118.3 |
| 8 AWG | 3.264 | 0.1285 | 8.37 | 2.061 | 3.379 | 74.4 |
| 10 AWG | 2.588 | 0.1019 | 5.26 | 3.277 | 5.372 | 46.8 |
| 12 AWG | 2.053 | 0.0808 | 3.31 | 5.211 | 8.542 | 29.4 |
| 14 AWG | 1.628 | 0.0641 | 2.08 | 8.285 | 13.583 | 18.5 |
| 16 AWG | 1.291 | 0.0508 | 1.31 | 13.174 | 21.597 | 11.6 |
| 18 AWG | 1.024 | 0.0403 | 0.823 | 20.948 | 34.341 | 7.3 |
| 20 AWG | 0.812 | 0.0320 | 0.518 | 33.308 | 54.604 | 4.6 |
| 22 AWG | 0.644 | 0.0253 | 0.326 | 52.962 | 86.824 | 2.9 |
| 24 AWG | 0.511 | 0.0201 | 0.205 | 84.213 | 138.055 | 1.8 |
Solid conductor values at 20 °C. Stranded conductors have a slightly larger overall diameter for the same area. kcmil diameters are for the equivalent solid area.
| mm² | Nearest AWG (by area) | Nearest common size | Diameter (mm) | Ω/km Cu | Ampacity* (A) |
|---|---|---|---|---|---|
| 0.5 | 20 AWG | 20 AWG | 0.80 | 36 | — |
| 0.75 | 18 AWG | 18 AWG | 0.98 | 24.5 | — |
| 1 | 17 AWG | 18 AWG | 1.13 | 18.1 | — |
| 1.5 | 15 AWG | 16 AWG | 1.38 | 12.1 | 17.5 |
| 2.5 | 13 AWG | 14 AWG | 1.78 | 7.41 | 24 |
| 4 | 11 AWG | 12 AWG | 2.26 | 4.61 | 32 |
| 6 | 9 AWG | 10 AWG | 2.76 | 3.08 | 41 |
| 10 | 7 AWG | 8 AWG | 3.57 | 1.83 | 57 |
| 16 | 5 AWG | 6 AWG | 4.51 | 1.15 | 76 |
| 25 | 3 AWG | 3 AWG | 5.64 | 0.727 | 101 |
| 35 | 2 AWG | 2 AWG | 6.68 | 0.524 | 125 |
| 50 | 1/0 AWG | 1/0 AWG | 7.98 | 0.387 | 151 |
| 70 | 2/0 AWG | 2/0 AWG | 9.44 | 0.268 | 192 |
| 95 | 3/0 AWG | 3/0 AWG | 11.00 | 0.193 | 232 |
| 120 | 250 kcmil | 250 kcmil | 12.36 | 0.153 | 269 |
| 150 | 300 kcmil | 300 kcmil | 13.82 | 0.124 | 309 |
| 185 | 350 kcmil | 350 kcmil | 15.35 | 0.0991 | 353 |
| 240 | 500 kcmil | 500 kcmil | 17.48 | 0.0754 | 415 |
"Nearest AWG" can be an odd gauge such as 13 AWG that is rarely stocked; "Nearest common size" picks from the sizes in the AWG table. * IEC 60364-5-52 / BS 7671, single-core PVC copper cables, reference method C (clipped direct), 30 °C, one circuit, the same values as the Cable Size Calculator. Resistance per IEC 60228 at 20 °C.
| AWG / kcmil | 60 °C (TW, UF) | 75 °C (THW, THWN) | 90 °C (THHN) |
|---|---|---|---|
| 14 AWG | 15 | 20 | 25 |
| 12 AWG | 20 | 25 | 30 |
| 10 AWG | 30 | 35 | 40 |
| 8 AWG | 40 | 50 | 55 |
| 6 AWG | 55 | 65 | 75 |
| 4 AWG | 70 | 85 | 95 |
| 3 AWG | 85 | 100 | 115 |
| 2 AWG | 95 | 115 | 130 |
| 1 AWG | 110 | 130 | 145 |
| 1/0 AWG | 125 | 150 | 170 |
| 2/0 AWG | 145 | 175 | 195 |
| 3/0 AWG | 165 | 200 | 225 |
| 4/0 AWG | 195 | 230 | 260 |
| 250 kcmil | 215 | 255 | 290 |
| 300 kcmil | 240 | 285 | 320 |
| 350 kcmil | 260 | 310 | 350 |
| 400 kcmil | 280 | 335 | 380 |
| 500 kcmil | 320 | 380 | 430 |
| 600 kcmil | 350 | 420 | 475 |
Not more than three current-carrying conductors. NEC 240.4(D) limits overcurrent protection to 15 A for 14 AWG, 20 A for 12 AWG and 30 A for 10 AWG copper.
American Wire Gauge (AWG) is a logarithmic scale: a smaller number is a thicker wire. Every 3 gauges the cross-sectional area halves, and every 6 gauges the diameter halves. Sizes above 1 AWG continue as 1/0, 2/0, 3/0 and 4/0 (also written 0, 00, 000 and 0000), and anything larger is given in kcmil (thousand circular mils).
Metric cables are sold directly by cross-sectional area in mm² (1.5, 2.5, 4, 6, 10, 16 mm² and so on), so the two systems never line up exactly. When converting a design, pick the metric size whose area is equal to or larger than the AWG size, then check ampacity and voltage drop for the actual installation with the Cable Size Calculator and the Voltage Drop Calculator.
12 AWG is 3.31 mm² (2.05 mm diameter). It sits between the metric sizes 2.5 mm² and 4 mm²; use 4 mm² as the metric equivalent so the conductor is not smaller.
2.5 mm² is closest to 13 AWG (2.63 mm²), a size rarely stocked. The common US sizes either side are 14 AWG (2.08 mm²) and 12 AWG (3.31 mm²); choose 12 AWG when the conductor must be at least as large.
Yes. Every 3 gauge numbers halves the cross-sectional area, and every 6 gauge numbers halves the diameter. 10 AWG has about twice the area of 13 AWG and four times the area of 16 AWG.
Diameter d = 0.127 mm × 92^((36 − n)/39), where n is the gauge number (use 0 for 1/0, −1 for 2/0, −2 for 3/0 and −3 for 4/0). Then area = π × d² / 4. For 10 AWG, d = 2.588 mm and area = 5.26 mm².
One kcmil (thousand circular mils, also written MCM) is 0.5067 mm². Sizes larger than 4/0 AWG are given in kcmil, for example 250 kcmil = 126.7 mm² and 500 kcmil = 253.4 mm².
Use the 75 °C column for most circuits, because equipment terminals are usually rated 75 °C (60 °C for many devices up to 100 A). The 90 °C column may be used for derating, but the result cannot exceed the termination rating.
Found a number that looks wrong, or a case the tool does not cover? Say so here — corrections are welcome and get answered.
No comments yet. Be the first to add one.