Wire gauges are typically denoted using the American Wire Gauge (AWG), also known as Brown and Sharpe Wire Guage.

The higher the gauge number, the thinner the wire. Telephone/network wires are typically AWG 24 or 26.

Gauge Table

AWG #	Diameter (inch)	Diameter (mm)	Resistance Ω/1000m Copper
0000 (4/0)	0.4600	11.6840	0.16
000 (3/0)	0.4096	10.4049	0.20
00 (2/0)	0.3648	9.2658	0.26
0 (1/0)	0.3249	8.2515	0.32
1	0.2893	7.3481	0.41
2	0.2576	6.5437	0.51
3	0.2294	5.8273	0.65
4	0.2043	5.1894	0.81
5	0.1819	4.6213
6	0.1620	4.1154	1.3
7	0.1443	3.6649
8	0.1285	3.2636	2.1
9	0.1144	2.9064
10	0.1019	2.5882	3.3
11	0.0907	2.3048
12	0.0808	2.0525	5.2
13	0.0720	1.8278	6.6
14	0.0641	1.6277	8.2
15	0.0571	1.4495
16	0.0508	1.2908	13
17	0.0453	1.1495
18	0.0403	1.0237	21
19	0.0359	0.9116
20	0.0320	0.8118	34
21	0.0285	0.7229
22	0.0253	0.6438	52
23	0.0226	0.5733
24	0.0201	0.5106	88
25	0.0179	0.4547	108
26	0.0159	0.4049	133
27	0.0142	0.3606	180
28	0.0126	0.3211	216
29	0.0113	0.2859
30	0.0100	0.2546	352
31	0.0089	0.2268
32	0.0080	0.2019	556
33	0.0071	0.1798	663
34	0.0063	0.1601	862
35	0.0056	0.1426	1120
36	0.0050	0.1270	1326
37	0.0045	0.1131	1810
38	0.0040	0.1007	2210
39	0.0035	0.0897	2693
40	0.0031	0.0799	3448

Max current ratings

AWG	Typical Max. Current Load Ratings - Copper (amps)
	Single Core	Multicore
	Single Core	up to 3 cores	4 - 6 cores	7 - 24 cores	25 - 42 cores	43 and above
24	3.5	2	1.6	1.4	1.2	1.0
22	5.0	3	2.4	2.1	1.8	1.5
20	6.0	5	4.0	3.5	3.0	2.5
18	9.5	7	5.6	4.9	4.2	3.5
16	15	10	8.0	7.0	6.0	5.0
14	24	15	12	10	9.0	7.5
12	34	20	16	14	12	10
10	52	30	24	21	18	15
8	75	40	32	28	24	20
6	95	55	44	38	33	27
4	120	70	56	49	42	35
3	154	80	64	56	48	40
2	170	95	76	66	57	57
1	180	110	88	77	66	55