12 AWG in mm²
A 12 AWG solid conductor is 2.053 mm across, which gives an area of 3.309 mm². The nearest metric size is 4 mm². A 2.5 mm² cable is smaller than 12 AWG, so it is not a like-for-like swap.
Conductor area 3.309 mm² Open in the calculator
AWG to mm² converter
Convert between American Wire Gauge, square millimetres and kcmil, with the nearest standard size in each system.
Conductor area
3.309mm²
Check the values to see a result.
- Nearest metric size
- 4 mm²
- Area in kcmil
- 6.53 kcmil
- Diameter, solid conductor
- 2.053 mm
Nearest sizes are for comparison, not substitution.
How it’s calculated
- d = 0.005 in × 92(36 − n) ÷ 39=0.005 × 92(36 − 12) ÷ 39 × 25.4 mm=2.053 mm
- A = π × d² ÷ 4=3.142 × 2.053² ÷ 4=3.309 mm²
d = 0.005 in × 92(36 − n) ÷ 39A = π × d² ÷ 41 kcmil = 0.5067 mm²
12 AWG is 3.309 mm² (6.53 kcmil), with a solid diameter of 2.053 mm. The nearest metric size is 4 mm².
Tip: A metric cable is not a drop-in for the nearest AWG size: check its current rating and the terminal range of the equipment.
How to convert AWG to mm²
American Wire Gauge (AWG) numbers a conductor by its diameter: the larger the number, the thinner the wire. Metric cables are sold by cross-sectional area in mm², and North American sizes above 4/0 AWG are given in kcmil, thousands of circular mils. The calculator converts between the three and shows the nearest standard size in each system.
AWG to diameter
d = 0.005 in × 92(36 − n) ÷ 39
The gauge is defined by two fixed points: 36 AWG is 0.005 in across and 4/0 AWG is 0.46 in, with 39 equal ratio steps between them. The sizes 1/0 to 4/0 are gauges 0 to −3 in the formula.
Diameter to area
A = π × d² ÷ 4
Convert the diameter to millimetres (1 in = 25.4 mm) and take the area of the circle. 14 AWG is 1.628 mm across, so its area is 2.081 mm².
Area to kcmil
1 kcmil = 0.5067 mm²
A circular mil is the area of a circle one thousandth of an inch in diameter. 250 kcmil is 250 × 0.5067 = 126.7 mm².
Two rules of thumb follow from the definition. Every three gauges the area roughly doubles, and every ten gauges it changes about tenfold.
Metric sizes work differently. IEC 60228 names a nominal area (2.5 mm², 16 mm²) and defines each size by its maximum resistance, so the real copper area can differ slightly from the name.
Wire gauge examples
16 mm² in AWG
16 mm² is 31.58 kcmil, which falls between 6 AWG (13.3 mm²) and 4 AWG (21.15 mm²). Its equivalent gauge is 5.204 AWG and the nearest gauge is 5 AWG, a size that is seldom stocked, so in practice the choice is 4 AWG.
Nearest AWG size 5 AWG Open in the calculator
250 kcmil in mm²
250 kcmil is 250 × 0.5067 = 126.7 mm². The nearest metric size is 120 mm², which has slightly less copper; the next size up is 150 mm².
Conductor area 126.7 mm² Open in the calculator
mm² to AWG table
Standard metric sizes from IEC 60228 with their area in kcmil and the nearest AWG size. Above 4/0 AWG, North American cable is sized in kcmil.
| Metric size (mm²) | kcmil | Nearest AWG |
|---|---|---|
| 0.5 | 0.9868 | 20 |
| 0.75 | 1.48 | 18 |
| 1 | 1.974 | 17 |
| 1.5 | 2.96 | 15 |
| 2.5 | 4.934 | 13 |
| 4 | 7.894 | 11 |
| 6 | 11.84 | 9 |
| 10 | 19.74 | 7 |
| 16 | 31.58 | 5 |
| 25 | 49.34 | 3 |
| 35 | 69.07 | 2 |
| 50 | 98.68 | 1/0 |
| 70 | 138.1 | 2/0 |
| 95 | 187.5 | 3/0 |
| 120 | 236.8 | 4/0 |
| 150 | 296 | Above 4/0 |
| 185 | 365.1 | Above 4/0 |
| 240 | 473.6 | Above 4/0 |
| 300 | 592.1 | Above 4/0 |
AWG sizes in mm² and kcmil
Solid round conductor geometry from the AWG definition (NBS Handbook 100). Stranded conductors of the same gauge have a slightly larger overall diameter.
| AWG | Diameter (mm) | Area (mm²) | kcmil | Nearest metric (mm²) |
|---|---|---|---|---|
| 4/0 | 11.68 | 107.2 | 211.6 | 95 |
| 3/0 | 10.4 | 85.03 | 167.8 | 95 |
| 2/0 | 9.266 | 67.43 | 133.1 | 70 |
| 1/0 | 8.251 | 53.48 | 105.5 | 50 |
| 1 | 7.348 | 42.41 | 83.69 | 35 |
| 2 | 6.544 | 33.63 | 66.37 | 35 |
| 3 | 5.827 | 26.67 | 52.63 | 25 |
| 4 | 5.189 | 21.15 | 41.74 | 25 |
| 5 | 4.621 | 16.77 | 33.1 | 16 |
| 6 | 4.115 | 13.3 | 26.25 | 16 |
| 7 | 3.665 | 10.55 | 20.82 | 10 |
| 8 | 3.264 | 8.366 | 16.51 | 10 |
| 9 | 2.906 | 6.634 | 13.09 | 6 |
| 10 | 2.588 | 5.261 | 10.38 | 6 |
| 11 | 2.305 | 4.172 | 8.234 | 4 |
| 12 | 2.053 | 3.309 | 6.53 | 4 |
| 13 | 1.828 | 2.624 | 5.178 | 2.5 |
| 14 | 1.628 | 2.081 | 4.107 | 2.5 |
| 15 | 1.45 | 1.65 | 3.257 | 1.5 |
| 16 | 1.291 | 1.309 | 2.583 | 1.5 |
| 17 | 1.15 | 1.038 | 2.048 | 1 |
| 18 | 1.024 | 0.823 | 1.624 | 0.75 |
| 19 | 0.9116 | 0.6527 | 1.288 | 0.75 |
| 20 | 0.8118 | 0.5176 | 1.022 | 0.5 |
| 21 | 0.7229 | 0.4105 | 0.8101 | 0.5 |
| 22 | 0.6438 | 0.3255 | 0.6424 | 0.5 |
| 23 | 0.5733 | 0.2582 | 0.5095 | 0.5 |
| 24 | 0.5106 | 0.2047 | 0.404 | 0.5 |
| 25 | 0.4547 | 0.1624 | 0.3204 | 0.5 |
| 26 | 0.4049 | 0.1288 | 0.2541 | 0.5 |
| 27 | 0.3606 | 0.1021 | 0.2015 | 0.5 |
| 28 | 0.3211 | 0.08098 | 0.1598 | 0.5 |
| 29 | 0.2859 | 0.06422 | 0.1267 | 0.5 |
| 30 | 0.2546 | 0.05093 | 0.1005 | 0.5 |
| 31 | 0.2268 | 0.04039 | 0.0797 | 0.5 |
| 32 | 0.2019 | 0.03203 | 0.06321 | 0.5 |
| 33 | 0.1798 | 0.0254 | 0.05013 | 0.5 |
| 34 | 0.1601 | 0.02014 | 0.03975 | 0.5 |
| 35 | 0.1426 | 0.01597 | 0.03152 | 0.5 |
| 36 | 0.127 | 0.01267 | 0.025 | 0.5 |
| 37 | 0.1131 | 0.01005 | 0.01983 | 0.5 |
| 38 | 0.1007 | 0.007967 | 0.01572 | 0.5 |
| 39 | 0.08969 | 0.006318 | 0.01247 | 0.5 |
| 40 | 0.07987 | 0.00501 | 0.009888 | 0.5 |
Questions about wire gauge
How many mm² is 14 AWG?
2.081 mm². The metric sizes on either side are 1.5 mm² and 2.5 mm².
Is 2.5 mm² the same as 12 AWG or 14 AWG?
Neither. 2.5 mm² sits between 14 AWG (2.081 mm²) and 12 AWG (3.309 mm²), at an equivalent of 13.21 AWG.
Why does a bigger AWG number mean a thinner wire?
The number began as a count of how many times wire was drawn through a die to make it thinner. More passes gave a higher number and a smaller diameter.
What do 1/0, 2/0, 3/0 and 4/0 mean?
They are the sizes larger than 1 AWG, read “one aught” to “four aught”. In the formula they are gauges 0, −1, −2 and −3. Past 4/0 (107.2 mm²), sizes are given in kcmil.
Can I use the nearest metric cable in place of an AWG size?
Not without checking. Current ratings come from the cable standard and the installation method, not from area alone, and equipment terminals accept a stated range of sizes. Use the conversion to find candidates, then check the rating tables that apply to the installation.
Limits of this result
- Nearest AWG and common nominal metric sizes are comparisons, not substitutions; confirm the conductor standard, material, class and manufacturer table used for the installation.
- Calculated diameter is bare solid-round geometry. Finished cable diameter depends on stranding, compaction, insulation, screen, armour and sheath construction.