What is the conversion between AWG and the metric system?

AWG or American Wire Gauge is the US standard measure for the diameter of electrical conductors. It is dissimilar to the metric system which is based on wire cross sectional area (in square mm) as defined in IEC 60228. The American Wire Gauge chart is based on the number of wire drawing operations employed to reduce the diameter of the wire to the required dimension. For example, a 26 gauge (AWG) wire requires more passes through the system of reducing dies than the 0000 or 4/0 wire (which is the largest AWG size) does.

As a general rule of thumb, the higher the AWG number, the smaller (or thinner) the wire will be. 

What are AWG and MCM sizes?

AWG is determined by first figuring out the radius of a wire squared, time pi. Oftentimes the term “circular mil” is used. Circular mil is the area of a 1/1000 (or 1 mil) diameter circle. Such measurements are made on only the wire and not on the wire’s jacketing or insulation. In fact, jacketing and insulation are not size determining factors of AWG. 

Above 0000 AWG, which equates to circa 110 mm sq, the US standard measure used is known as circular mils (a mil is defined as 1000^th of an inch)- as opposed to square millimetres, circular mils are the area of the circle with 1mil diameter. One MCM is equivalent to 1000 circular mils. For comparison, 1 MCM equates to 0.5067 square mm, so for many purposes , a ratio of 2MCM to 1mmsq can be used with a 1.3% (very small) error. Our Belden cables and the pairs in data and instrumentation cable are some of the electrical cables where the conductor size is/can be expressed as an AWG figure. Our Tri-Rated cable, compliant with American standard UL758, can be converted to AWG cable conductor sizes if required.

The most common method of referring to conductor sizes uses the cross-sectional area, expressed in mm². The following AWG metric conversion table converts AWG to mm and inches, and also lists the cross sectional area (mm2).  It should always be borne in mind that the primary factor for conductors in accordance with IEC 60228 is based on the resistance of the conductor, so this should also be taken into account when cross referring AWG to mmsq.

AWG/MCM Metric Conversion Chart (AWG to mm2)

American Wire Gauge (AWG)	Diameter (in)	Diameter (mm)	Cross sectional area (mm2)
0000 (4/0)	0.460	11.7	107.0
000 (3/0)	0.410	10.4	85.0
00 (2/0)	0.365	9.27	67.4
0 (1/0)	0.325	8.25	53.5
1	0.289	7.35	42.4
2	0.258	6.54	33.6
3	0.229	5.83	26.7
4	0.204	5.19	21.1
5	0.182	4.62	16.8
6	0.162	4.11	13.3
7	0.144	3.67	10.6
8	0.129	3.26	8.36
9	0.114	2.91	6.63
10	0.102	2.59	5.26
11	0.0.907	2.30	4.17
12	0.0808	2.05	3.31
13	0.0720	1.83	2.63
14	0.0641	1.63	2.08
15	0.0571	1.45	1.65
16	0.0508	1.29	1.31
17	0.0453	1.15	1.04
18	0.0403	1.02	0.82
19	0.0359	0.91	0.65
20	0.0320	0.81	0.52
21	0.0285	0.72	0.41
22	0.0254	0.65	0.33
23	0.0226	0.57	0.26
24	0.0201	0.51	0.20
25	0.0179	0.45	0.16
26	0.0159	0.40	0.13

 

AWG and Resistance

AWG is also related to resistance. Resistance acts upon both a direct current and alternating current to create a “skin effect.” Simply put, as a signal frequency increases, the current flow of the wire concentrates toward the skin (outside) of the conductor. If you measured the resistance at different frequencies, you’d find that the resistance increases as frequency increases. Essentially, a thicker wire will have less resistance and carry more voltage at a longer distance.

Choosing the Right AWG Wire Size

Choosing a wire size will depend on the gauge and length you need. To determine the gauge wire you need, consider what carrying capacity and amount of current the wire needs to conduct to work for your application. Now consider the distance. The distance your wire needs to go can impact the gauge size you need. The longer the wire, the more voltage you can lose through resistance and heat. One way to counteract voltage drop is by increasing the wire gauge, which increases your amperage capacity, allowing you to pump more amperage through and ultimately, give you enough electricity for the intended application.

If this AWG metric calculator doesn't provide you with the information you need, please get in touch with the technical experts of The Cable Lab who will be pleased to answer your questions or calculate the appropriate AWG/metric size for your installation.

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