AWG to mm2 Converter and Wire Gauge Chart

AWG to mm2 in short: 12 AWG is 3.31 mm² (2.05 mm diameter), 14 AWG is 2.08 mm², 16 AWG is 1.31 mm² and 18 AWG is 0.82 mm². The lower the gauge number, the thicker the wire; going down three gauges doubles the cross-section. The converter also shows the nearest metric size.

Example: Conversion: AWG → mm² and diameter · Wire gauge (AWG): 12 → Result: 12 AWG = 3.309 mm² (2.053 mm diameter). Source: NBS HB 100, NBS Handbook 100 – Copper Wire Tables (1966): American Wire Gage definition and annealed copper standard. Updated: 30 September 2026.

Conversion

Wire gauge (AWG)

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Result

Result: 12 AWG = 3.309 mm² (2.053 mm diameter)
Values: Quantity Value
AWG 12
Diameter 2.053 mm = 0.0808 in
Cross-section 3.309 mm² = 6.53 kcmil
Copper resistance (20 °C) 5.211 Ω/km = 1.588 Ω/1000 ft
Next metric size (≥) 4 mm²
Step by step: Diameter: d = 0.127 mm · 92^((36 − 12) / 39) = 2.053 mm
Cross-section: A = π/4 · (2.053 mm)² = 3.309 mm²
Resistance: R = ρ / A = 17.241 Ω·mm²/km / 3.309 mm² = 5.211 Ω/km
AWG chart (solid wire, copper at 20 °C): AWG Ø mm Ø inch mm² Ω/km
0000 (4/0) 11.684 0.46 107.219 0.161
000 (3/0) 10.405 0.4096 85.029 0.203
00 (2/0) 9.266 0.3648 67.431 0.256
0 8.251 0.3249 53.475 0.322
1 7.348 0.2893 42.408 0.407
2 6.544 0.2576 33.631 0.513
3 5.827 0.2294 26.67 0.646
4 5.189 0.2043 21.151 0.815
5 4.621 0.1819 16.773 1.028
6 4.115 0.162 13.302 1.296
7 3.665 0.1443 10.549 1.634
8 3.264 0.1285 8.366 2.061
9 2.906 0.1144 6.634 2.599
10 2.588 0.1019 5.261 3.277
11 2.305 0.0907 4.172 4.132
12 2.053 0.0808 3.309 5.211
13 1.828 0.072 2.624 6.571
14 1.628 0.0641 2.081 8.286
15 1.45 0.0571 1.65 10.45
16 1.291 0.0508 1.309 13.17
17 1.15 0.0453 1.038 16.61
18 1.024 0.0403 0.823 20.95
19 0.912 0.0359 0.6527 26.42
20 0.812 0.032 0.5176 33.31
21 0.723 0.0285 0.4105 42
22 0.644 0.0253 0.3255 52.96
23 0.573 0.0226 0.2582 66.79
24 0.511 0.0201 0.2047 84.22
25 0.455 0.0179 0.1624 106.19
26 0.405 0.0159 0.1288 133.91
27 0.361 0.0142 0.1021 168.85
28 0.321 0.0126 0.081 212.92
29 0.286 0.0113 0.0642 268.49
30 0.255 0.01 0.0509 338.56
31 0.227 0.0089 0.0404 426.91
32 0.202 0.008 0.032 538.33
33 0.18 0.0071 0.0254 678.82
34 0.16 0.0063 0.0201 855.97
35 0.143 0.0056 0.016 1,079.36
36 0.127 0.005 0.0127 1,361.05
37 0.113 0.0045 0.01 1,716.25
38 0.101 0.004 0.008 2,164.16
39 0.09 0.0035 0.0063 2,728.95
40 0.08 0.0031 0.005 3,441.14

Quantity	Value
AWG	12
Diameter	2.053 mm = 0.0808 in
Cross-section	3.309 mm² = 6.53 kcmil
Copper resistance (20 °C)	5.211 Ω/km = 1.588 Ω/1000 ft
Next metric size (≥)	4 mm²

AWG	Ø mm	Ø inch	mm²	Ω/km
0000 (4/0)	11.684	0.46	107.219	0.161
000 (3/0)	10.405	0.4096	85.029	0.203
00 (2/0)	9.266	0.3648	67.431	0.256
0	8.251	0.3249	53.475	0.322
1	7.348	0.2893	42.408	0.407
2	6.544	0.2576	33.631	0.513
3	5.827	0.2294	26.67	0.646
4	5.189	0.2043	21.151	0.815
5	4.621	0.1819	16.773	1.028
6	4.115	0.162	13.302	1.296
7	3.665	0.1443	10.549	1.634
8	3.264	0.1285	8.366	2.061
9	2.906	0.1144	6.634	2.599
10	2.588	0.1019	5.261	3.277
11	2.305	0.0907	4.172	4.132
12	2.053	0.0808	3.309	5.211
13	1.828	0.072	2.624	6.571
14	1.628	0.0641	2.081	8.286
15	1.45	0.0571	1.65	10.45
16	1.291	0.0508	1.309	13.17
17	1.15	0.0453	1.038	16.61
18	1.024	0.0403	0.823	20.95
19	0.912	0.0359	0.6527	26.42
20	0.812	0.032	0.5176	33.31
21	0.723	0.0285	0.4105	42
22	0.644	0.0253	0.3255	52.96
23	0.573	0.0226	0.2582	66.79
24	0.511	0.0201	0.2047	84.22
25	0.455	0.0179	0.1624	106.19
26	0.405	0.0159	0.1288	133.91
27	0.361	0.0142	0.1021	168.85
28	0.321	0.0126	0.081	212.92
29	0.286	0.0113	0.0642	268.49
30	0.255	0.01	0.0509	338.56
31	0.227	0.0089	0.0404	426.91
32	0.202	0.008	0.032	538.33
33	0.18	0.0071	0.0254	678.82
34	0.16	0.0063	0.0201	855.97
35	0.143	0.0056	0.016	1,079.36
36	0.127	0.005	0.0127	1,361.05
37	0.113	0.0045	0.01	1,716.25
38	0.101	0.004	0.008	2,164.16
39	0.09	0.0035	0.0063	2,728.95
40	0.08	0.0031	0.005	3,441.14

How it is calculated

How the AWG system works

American Wire Gauge (AWG) is a numbered series of wire diameters defined by two points: 0000 AWG is 0.4600 inch (11.684 mm) and 36 AWG is 0.0050 inch (0.127 mm). The 38 steps in between form a geometric series – each gauge is thinner than the previous one by a factor of 92^(1/39) ≈ 1.123 (NBS Handbook 100, today ASTM B258). Therefore:

d = 0.127 mm · 92^((36 − n) / 39) · A = π/4 · d²

Rules of thumb: 6 gauges down doubles the diameter, 3 gauges down doubles the area, 10 gauges down gives ten times the area.

AWG to mm²: key values

AWG	Ø mm	mm²	next metric size
10	2.59	5.26	6 mm²
12	2.05	3.31	4 mm²
14	1.63	2.08	2.5 mm²
16	1.29	1.31	1.5 mm²
18	1.02	0.82	1 mm²
20	0.81	0.52	0.75 mm²
22	0.64	0.33	0.5 mm²

The full chart from 4/0 to 40 AWG is shown right below the converter. Metric cables come in nominal sizes per IEC 60228 (0.5 – 0.75 – 1 – 1.5 – 2.5 – 4 – 6 – 10 – 16 mm² …), which almost never match an AWG size exactly – when replacing an AWG cable, pick the next larger metric size.

Resistance and ampacity

Resistance values use the International Annealed Copper Standard (ρ = 1/58 Ω·mm²/m at 20 °C). How much current a cable may carry depends not only on its size but on installation method, bundling, ambient temperature and insulation rating – in the US that is governed by the NEC ampacity tables. This converter deliberately does not print an ampere value.

Stranded vs. solid wire

AWG values refer to solid wire. Stranded wire of the same gauge has roughly the same copper area but a slightly larger outer diameter because of the gaps between strands.

Frequently asked questions

What is 12 AWG in mm²?

12 AWG has a diameter of 2.05 mm and a cross-section of 3.31 mm². The closest metric replacement that is not thinner is 4 mm².

What AWG is 1.5 mm²?

1.5 mm² lies between 16 AWG (1.31 mm²) and 15 AWG (1.65 mm²). 16 AWG is the usual comparison but is slightly thinner.

What AWG is 2.5 mm²?

The closest is 13 AWG (2.62 mm²); the common 14 AWG (2.08 mm²) has about 17 % less copper.

What does 4/0 AWG mean?

Gauges thicker than 1 AWG are written 0, 00, 000 and 0000, or 1/0 to 4/0. 4/0 AWG is 11.68 mm in diameter and 107.2 mm² (211.6 kcmil).

What is the formula to convert AWG to mm²?

Diameter d = 0.127 mm · 92^((36 − AWG)/39), then area A = π/4 · d². For 18 AWG: d = 1.024 mm, A = 0.823 mm².

Sources and legal basis

NBS HB 100: NBS Handbook 100 – Copper Wire Tables (1966): American Wire Gage definition and annealed copper standard
IEC 60228:2023: IEC 60228:2023 – Conductors of insulated cables (nominal cross-sectional areas 0.5–3500 mm²)

As of: 30 September 2026