BWG - Birmingham Wire Gauge

Used to determine wall thickness of pipe - in gauge and decimal parts of inch.

Birmingham Wire Gauge - BWG - is also known as Stubs' Wire Gauge used for drill rod and tool steel wire.

A cross reference between BWG, imperial sizes and metric equivalents, in terms of tube wall thickness:

BWG - Birmingham Wire Gauge
Birmingham Wire Gage BWG	(inches)	(mm)
00000 (5/0)	0.500
0000 (4/0)	0.454
000 (3/0)	0.425
00 (2/0)	0.380
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
27	0.016
28	0.014
29	0.013
30	0.012
31	0.010
32	0.009
33	0.008
34	0.007
35	0.005
36	0.004

The wall thickness of a pipe is normally given in decimal parts of an inch rather than as a fraction or gauge number. When gauge number is given for a pipe without reference to a system, Birmingham Wire Gauge - BWG - is implied.