The Birmingham wire gauge (BWG), also known as Birmingham gauge or Stubs’ iron wire gauge, is a prevalent wire gauge system for determination of diameter of steel wires and thickness of steel sheets. It is also extensively used for specifying the wall thickness of stainless steel tubing. There are a variety of gauge systems such as the Stubs steel wire gauge, American wire gauge (also known as AWG, or Brown and Sharpe gauge), Steel wire gauge (also known as Washburn and Moen gauge), U.S. standard gauge, and British standard gauge, etc. Although similar to each other, these gauge systems are not interchangeable. In fact, when a gauge number given to the tubing wall thickness doesn’t specify a reference gauge system, Birmingham wire gauge is implied.

BWG Correspondence: Gauge no. – inch – mm

Gauge No.	inch	mm
0000	0.454	11.532
000	0.425	10.795
00	0.380	9.652
0	0.340	8.636
1	0.300	7.620
2	0.284	7.214
3	0.259	6.579
4	0.238	6.045
5	0.220	5.588
6	0.203	5.156
7	0.180	4.572
8	0.165	4.191
9	0.148	3.759
10	0.134	3.404
11	0.120	3.048
12	0.109	2.769
13	0.095	2.413
14	0.083	2.108
15	0.072	1.829
16	0.065	1.651
17	0.058	1.473
18	0.049	1.245
19	0.042	1.067
20	0.035	0.889
21	0.032	0.813
22	0.028	0.711
23	0.025	0.635
24	0.022	0.559
25	0.020	0.508
26	0.018	0.457
27	0.016	0.406
28	0.014	0.356
29	0.013	0.330
30	0.012	0.305
31	0.010	0.254
32	0.009	0.229
33	0.008	0.203
34	0.007	0.178
35	0.005	0.127
36	0.004	0.102

*The BWG contains 40 gauge numbers from 0000, 000, 00, 0 to 36. The weights of commercial tubing made of stainless steel, carbon and alloy steel are available upon request.