AWG Wire Gauge Table

American Wire Gauge 0000 to 40: diameter, area, copper resistance and mass.

American Wire Gauge (AWG) is the wire size system used for electrical conductors in North America. Like sheet gauge, a larger number means a thinner wire, but AWG is a true geometric series: every 6 gauge steps halve the diameter, and every 3 steps halve the area. This table gives the bare copper dimensions and resistance for every size from 0000 (4/0) to 40.

The table

44 rows

AWG	Diameter (mm)	Diameter (in)	Area (mm2)	Resistance, copper at 20 C (ohm/km)	Resistance (ohm per 1000 ft)	Copper mass (kg/km)
0000 (4/0)	11.684	0.46	107.219	0.161	0.049	960.685
000 (3/0)	10.4049	0.40964	85.0288	0.203	0.062	761.858
00 (2/0)	9.2658	0.3648	67.4309	0.256	0.078	604.181
0 (1/0)	8.2515	0.32486	53.4751	0.322	0.098	479.137
1	7.3481	0.2893	42.4077	0.407	0.124	379.973
2	6.5437	0.25763	33.6308	0.513	0.156	301.332
3	5.8273	0.22942	26.6705	0.646	0.197	238.967
4	5.1894	0.20431	21.1506	0.815	0.248	189.51
5	4.6213	0.18194	16.7732	1.028	0.313	150.288
6	4.1154	0.16202	13.3018	1.296	0.395	119.184
7	3.6649	0.14429	10.5488	1.634	0.498	94.517
8	3.2636	0.12849	8.3656	2.061	0.628	74.955
9	2.9064	0.11442	6.6342	2.599	0.792	59.442
10	2.5882	0.1019	5.2612	3.277	0.999	47.14
11	2.3048	0.09074	4.1723	4.132	1.26	37.384
12	2.0525	0.08081	3.3088	5.211	1.588	29.647
13	1.8278	0.07196	2.624	6.571	2.003	23.511
14	1.6277	0.06408	2.0809	8.285	2.525	18.645
15	1.4495	0.05707	1.6502	10.448	3.184	14.786
16	1.2908	0.05082	1.3087	13.174	4.015	11.726
17	1.1495	0.04526	1.0378	16.612	5.063	9.299
18	1.0237	0.0403	0.823	20.948	6.385	7.374
19	0.9116	0.03589	0.6527	26.415	8.051	5.848
20	0.8118	0.03196	0.5176	33.308	10.152	4.638
21	0.7229	0.02846	0.4105	42.001	12.802	3.678
22	0.6438	0.02535	0.3255	52.962	16.143	2.917
23	0.5733	0.02257	0.2582	66.784	20.356	2.313
24	0.5106	0.0201	0.2047	84.213	25.668	1.834
25	0.4547	0.0179	0.1624	106.191	32.367	1.455
26	0.4049	0.01594	0.1288	133.904	40.814	1.154
27	0.3606	0.0142	0.1021	168.85	51.466	0.915
28	0.3211	0.01264	0.081	212.916	64.897	0.726
29	0.2859	0.01126	0.0642	268.482	81.833	0.575
30	0.2546	0.01003	0.0509	338.55	103.19	0.456
31	0.2268	0.00893	0.0404	426.904	130.12	0.362
32	0.2019	0.00795	0.032	538.315	164.079	0.287
33	0.1798	0.00708	0.0254	678.803	206.899	0.228
34	0.1601	0.0063	0.0201	855.955	260.895	0.18
35	0.1426	0.00561	0.016	1079.34	328.983	0.143
36	0.127	0.005	0.0127	1361.02	414.839	0.114
37	0.1131	0.00445	0.01	1716.22	523.103	0.09
38	0.1007	0.00397	0.008	2164.11	659.621	0.071
39	0.0897	0.00353	0.0063	2728.89	831.766	0.057
40	0.0799	0.00314	0.005	3441.07	1048.84	0.045

Source and notes: ASTM B258: d = 0.127 mm x 92^((36 - n) / 39). Copper resistivity 1.7241e-8 ohm m, density 8 960 kg/m3.

How to use this table

Find the AWG number (sizes 0000, 000 and 00 are written 4/0, 3/0 and 2/0).
Read the diameter for hole and connector sizes and the area for current capacity and voltage drop.
Use the resistance per kilometer (or per 1 000 ft) for voltage drop and power loss.

Worked example: 14 AWG copper, 25 m run, 15 A load on a 120 V circuit

14 AWG is 1.628 mm across with an area of 2.081 mm² and a resistance of 8.285 ohm/km at 20 C.
The current flows out and back, so the conductor length is 2 × 25 m = 50 m: R = 50 × 8.285 ÷ 1 000 = 0.414 ohm.
Voltage drop = I × R = 15 × 0.414 = 6.21 V, which is 5.2 percent of 120 V. That is over the 3 percent usually recommended, so a thicker wire (12 AWG) is the better choice.

Notes and cautions

Current rating (ampacity) depends on the insulation, the installation and the code in force. It is not a property of the gauge alone: use the ampacity tool and the applicable code.
Resistance rises with temperature, by about 0.39 percent per degree C for copper. The table is for 20 C.
Stranded wire has slightly more resistance than a solid conductor of the same AWG size because of the lay of the strands.

FAQ

What is the diameter of 12 AWG wire?

About 2.05 mm (0.0808 inch) for bare solid copper, with an area of 3.31 mm².

What happens every 6 AWG steps?

The diameter doubles or halves. Every 3 steps the area, and so the weight, doubles or halves, and the resistance does the opposite.

Which AWG for 15 amps?

Common practice in North American building wiring is 14 AWG for 15 A and 12 AWG for 20 A, subject to the code and the installation. See the ampacity tool.

Sources

ASTM B258, Standard Specification for Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires.
ASTM B258: d = 0.127 mm x 92^((36 – n) / 39). Copper resistivity 1.7241e-8 ohm m, density 8 960 kg/m3.