AWG wire diameter in mm

The American Wire Gauge (AWG) is a standardized logarithmic system for sizing electrical conductors, used primarily in North America since 1857. ASTM B-258 defines the nominal diameters of solid round conductors. The higher the gauge number, the smaller the wire diameter: a 24 AWG wire has a diameter of 0,51 mm / 0.0201 in, while a 10 AWG reaches 2,59 mm / 0.102 in. The following table lists the diameters and cross-sectional areas for the most commonly used gauges.

AWG to Millimeters Conversion Table

AWG Gauge	Diameter (mm / in)	Cross-sectional area (mm² / in²)
0000 (4/0)	11,7 mm / 0.460 in	107 mm² / 0.166 in²
000 (3/0)	10,4 mm / 0.410 in	85,0 mm² / 0.132 in²
00 (2/0)	9,27 mm / 0.365 in	67,4 mm² / 0.105 in²
0 (1/0)	8,25 mm / 0.325 in	53,5 mm² / 0.083 in²
1	7,35 mm / 0.289 in	42,4 mm² / 0.066 in²
2	6,54 mm / 0.258 in	33,6 mm² / 0.052 in²
3	5,83 mm / 0.229 in	26,7 mm² / 0.041 in²
4	5,19 mm / 0.204 in	21,1 mm² / 0.033 in²
5	4,62 mm / 0.182 in	16,8 mm² / 0.026 in²
6	4,11 mm / 0.162 in	13,3 mm² / 0.021 in²
7	3,67 mm / 0.144 in	10,6 mm² / 0.016 in²
8	3,26 mm / 0.129 in	8,36 mm² / 0.0130 in²
9	2,91 mm / 0.114 in	6,63 mm² / 0.0103 in²
10	2,59 mm / 0.102 in	5,26 mm² / 0.00816 in²
11	2,30 mm / 0.0907 in	4,17 mm² / 0.00646 in²
12	2,05 mm / 0.0808 in	3,31 mm² / 0.00513 in²
13	1,83 mm / 0.0720 in	2,63 mm² / 0.00407 in²
14	1,63 mm / 0.0641 in	2,08 mm² / 0.00323 in²
15	1,45 mm / 0.0571 in	1,65 mm² / 0.00256 in²
16	1,29 mm / 0.0508 in	1,31 mm² / 0.00203 in²
17	1,15 mm / 0.0453 in	1,04 mm² / 0.00161 in²
18	1,02 mm / 0.0403 in	0,82 mm² / 0.00127 in²
19	0,91 mm / 0.0359 in	0,65 mm² / 0.00101 in²
20	0,81 mm / 0.0320 in	0,52 mm² / 0.00080 in²
21	0,72 mm / 0.0285 in	0,41 mm² / 0.00064 in²
22	0,65 mm / 0.0254 in	0,33 mm² / 0.00051 in²
23	0,57 mm / 0.0226 in	0,26 mm² / 0.00040 in²
24	0,51 mm / 0.0201 in	0,20 mm² / 0.00031 in²
25	0,45 mm / 0.0179 in	0,16 mm² / 0.00025 in²
26	0,40 mm / 0.0159 in	0,13 mm² / 0.00020 in²

Note: the diameter of a stranded conductor with the same AWG is larger than that of a solid conductor due to the spaces between the strands.

AWG Diameter Calculation Formula

The nominal diameter of a solid round conductor is calculated using a geometric progression based on the gauge number. For an AWG gauge n (where n ranges from 36 to 0, and n = -1 for 00, n = -2 for 000, n = -3 for 0000), the diameter in millimeters and in inches is:

dₙ = 0,127 mm × 92^((36-n)/39) = 0,005 in × 92^((36-n)/39)

This is equivalent to the exponential expression:

dₙ = e^(2,1104 – 0,11594 n) mm

Where:

n: AWG number (36 to 0; negative values for gauges larger than 0).
dₙ: diameter of the solid conductor (mm or in).
The ratio between successive gauges is 92^(1/39) ≈ 1,1229.

Relationship between AWG and Cross-sectional Area

The cross-sectional area is derived directly from the diameter. For a round conductor, the area Aₙ is:

Aₙ = (π/4) dₙ² ≈ 0,012668 mm² × 92^((36-n)/19,5)

The AWG system is logarithmic, which implies practical scaling rules:

A reduction of 3 AWG numbers approximately doubles the cross-sectional area and conductance (for example, two 14 AWG wires are equivalent in area to one 11 AWG).
A reduction of 6 AWG numbers doubles the diameter and quadruples the cross-sectional area (for example, 1 mm ≈ 18 AWG, 2 mm ≈ 12 AWG, 4 mm ≈ 6 AWG).
A reduction of 10 AWG numbers multiplies the area, weight, and conductance by approximately 10.

For illustration, the following table shows how diameter and area vary in steps of 6 gauges:

AWG Gauge	Diameter (mm / in)	Cross-sectional area (mm² / in²)
10	2,59 mm / 0.102 in	5,26 mm² / 0.00816 in²
16	1,29 mm / 0.0508 in	1,31 mm² / 0.00203 in²
4	5,19 mm / 0.204 in	21,1 mm² / 0.033 in²

Frequently Asked Questions (FAQ)

How do I convert an AWG gauge to millimeters?

Use the standard formula dₙ(mm) = 0,127 × 92^((36-n)/39), where n is the AWG number. For gauges thicker than 0, n takes negative values: -1 for 00, -2 for 000, and -3 for 0000. The conversion table in this article provides pre-calculated values.

What is the diameter in mm of the largest gauges such as 4/0 AWG?

Gauge 0000 AWG (4/0) has a diameter of 11,7 mm / 0.460 in. 000 AWG (3/0) measures 10,4 mm / 0.410 in and 00 AWG (2/0) measures 9,27 mm / 0.365 in.

Why is the diameter of a stranded cable with the same AWG larger than that of a solid cable?

Because the AWG of a stranded cable is defined by the equivalent cross-sectional area of the solid conductor. Since there are small gaps between the individual strands, the overall outer diameter is always larger than that of a solid conductor of the same gauge.

What is the difference between AWG and cross-sectional area in mm²?

AWG indicates a gauge number based on conductor diameter, while the area in mm² directly describes the cross-sectional area of the conductor material. The relationship between them is logarithmic: a lower AWG number means a larger diameter and therefore a larger cross-sectional area.

After how many AWG numbers does the diameter or cross-sectional area double?

Approximately every 6 AWG numbers the conductor diameter doubles (and the cross-sectional area quadruples). Every 3 AWG numbers the cross-sectional area doubles. For example, going from 16 AWG (1,29 mm, 1,31 mm²) to 10 AWG (2,59 mm, 5,26 mm²) reduces the gauge by 6 and doubles the diameter.

Where is the AWG system primarily used?

The AWG system is predominantly used in North America (United States, Canada, and Mexico) to designate the gauge of copper and aluminum electrical conductors. The rest of the world predominantly uses the metric system based on cross-sectional area in mm² according to IEC 60228.

Sources Consulted

engineeringtoolbox.com: https://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html
electrical4u.com: https://www.electrical4u.com/electrical-power-cable/
southwire.com: https://www.southwire.com/medias/2304-American-Wire-Gauge-PRINT.pdf?context=bWFzdGVyfHJvb3R8MjQyMTE2fGFwcGxpY2F0aW9uL3BkZnxoYjIvaGJjLzkyMjU2NjM3NDE5ODIvMjMwNF9BbWVyaWNhbl9XaXJlX0dhdWdlX1BSSU5ULnBkZnwxNTlkMGY2OWM2NTQzNDBhYmZiMzE5ZDFlYWRjNTRlMzhjMDU0NTljMjgxM2EyM2I4ZWRkZWFhMWI2NDJjZDRl