Metal Sheet Gauge inches to mm Conversion Chart

In the steel industry, the term “Gauge” is often used. Gauge represents the thickness of the metal sheet. Different gauge codes have different thicknesses.

Gauges are commonly measured in inches and millimeters. How do you trade off the two? You can find the conversion of galvanized steel, stainless steel, aluminum, and mild steel gauge inches to millimeters in the table below.

For metal sheet gauges, the larger the gauge code, the thinner the metal sheet is. For example, for metal sheets of the same material, gauge 18 is thicker than gauge 20. You can clearly see this from the table.

Gauge(Ga.)	Standard Steel Thickness (inches)	Standard Steel Thickness (mm)	Galvanized Steel Thickness (inches)	Galvanized Steel Thickness (mm)	Aluminum (inches)	Aluminum Thickness (mm)
3	0.2391	6.07314			0.2294	5.82676
4	0.2242	5.69468			0.2043	5.18922
5	0.2092	5.31368			0.1819	4.62026
6	0.1943	4.93522			0.162	4.1148
7	0.1793	4.55422			0.1443	3.66522
8	0.1644	4.17576			0.1285	3.2639
9	0.1495	3.7973	0.1532	3.89128	0.1144	2.90576
10	0.1345	3.4163	0.1382	3.51028	0.1019	2.58826
11	0.1196	3.03784	0.1233	3.13182	0.0907	2.30378
12	0.1046	2.65684	0.1084	2.75336	0.0808	2.05232
13	0.0897	2.27838	0.0934	2.37236	0.072	1.8288
14	0.0747	1.89738	0.0785	1.9939	0.0641	1.62814
15	0.0673	1.70942	0.071	1.8034	0.0571	1.45034
16	0.0598	1.51892	0.0635	1.6129	0.0508	1.29032
17	0.0538	1.36652	0.0575	1.4605	0.0453	1.15062
18	0.0478	1.21412	0.0516	1.31064	0.0403	1.02362
19	0.0418	1.06172	0.0456	0.15824	0.0359	0.91186
20	0.0359	0.91186	0.0396	1.00584	0.032	0.8128
21	0.0329	0.83566	0.0366	0.92964	0.0285	0.7239
22	0.0299	0.75946	0.0336	0.85344	0.0253	0.64262
23	0.0269	0.68326	0.0306	0.77724	0.0226	0.57404
24	0.0239	0.60706	0.0276	0.7004	0.0201	0.51054
25	0.0209	0.53086	0.0247	0.62738	0.0179	0.45466
26	0.0179	0.45466	0.0217	0.55118	0.0159	0.40386
27	0.0164	0.41656	0.0202	0.51308	0.0142	0.36068
28	0.0149	0.37846	0.0187	0.47498	0.0126	0.32004
29	0.035	0.3429	0.0172	0.43688	0.0113	0.28702
30	0.012	0.3048	0.0157	0.39878	0.01	0.254
31	0.0105	0.2667	0.0142	0.36068	0.0089	0.22606
32	0.0097	0.24638	0.0134	0.34036	0.008	0.2032
33	0.009	0.2286			0.0071	0.18034
34	0.0082	0.20828			0.0063	0.16002
35	0.0075	0.1905			0.0056	0.14224
36	0.0067	0.17018

Gauges of different countries

Gauge Number	UK Gauge		Birmingham Gauge		American Gauge
	inches	mm	inches	mm	inches	mm
3	0.252	6.401	0.259	6.58	0.2294	5.83
4	0.232	5.893	0.238	6.05	0.2043	5.19
5	0.212	5.385	0.22	5.59	0.1819	4.62
6	0.192	4.877	0.203	5.16	0.162	4.11
7	0.176	4.47	0.18	4.57	0.1443	3.67
8	0.16	4.064	0.165	4.19	0.1285	3.26
9	0.144	3.658	0.148	3.76	0.1144	2.91
10	0.128	3.251	0.134	3.4	0.1019	2.59
11	0.116	2.946	0.12	3.05	0.09074	2.3
12	0.104	2.642	0.109	2.77	0.08081	2.05
13	0.092	2.337	0.095	2.41	0.07196	1.83
14	0.08	2.032	0.083	2.11	0.06408	1.63
15	0.072	1.829	0.072	1.83	0.05707	1.45
16	0.064	1.626	0.065	1.65	0.05082	1.29
17	0.056	1.422	0.058	1.47	0.04526	1.15
18	0.048	1.219	0.049	1.24	0.0403	1.02
19	0.04	1.016	0.042	1.07	0.03589	0.91
20	0.036	0.914	0.035	0.89	0.03196	0.812
21	0.032	0.813	0.032	0.81	0.02846	0.723
22	0.028	0.711	0.028	0.71	0.02535	0.644
23	0.024	0.61	0.025	0.64	0.02257	0.573
24	0.022	0.559	0.022	0.56	0.0201	0.511
25	0.02	0.508	0.02	0.51	0.0179	0.455
26	0.018	0.457	0.018	0.46	0.01594	0.405
27	0.0164	0.4166	0.016	0.41	0.0142	0.361
28	0.0148	0.3759	0.014	0.36	0.01264	0.321
29	0.0136	0.3454	0.013	0.33	0.01126	0.286
30	0.0124	0.315	0.012	0.3	0.01003	0.255
31	0.0116	0.2946	0.01	0.25	0.008928	0.227
32	0.0108	0.2743	0.009	0.23	0.00795	0.202
33	0.01	0.254	0.008	0.2	0.00708	0.18
34	0.0092	0.2337	0.007	0.18	0.006304	0.16
35	0.0084	0.2134	0.005	0.13	0.005615	0.143
36	0.0076	0.193	0.004	0.1	0.005	0.127

Galvanized Steel Gauge inches to mm Conversion Chart

Galvanized Steel Gauge Number	inches	mm
8	0.1681	4.27
9	0.1532	3.8913
10	0.1382	3.5103
11	0.1233	3.1318
12	0.1084	2.7534
13	0.0934	2.3724
14	0.0785	1.9939
15	0.071	1.8034
16	0.0635	1.6129
17	0.0575	1.4605
18	0.0516	1.3106
19	0.0456	1.1582
20	0.0396	1.0058
21	0.0366	0.9296
22	0.0336	0.8531
23	0.0306	0.7772
24	0.0276	0.7004
25	0.0247	0.6274
26	0.0217	0.5512
27	0.0202	0.5131
28	0.0187	0.475
29	0.0172	0.4369
30	0.0157	0.3988
31	0.0142	0.3607
32	0.0134	0.3404

Stainless Steel Gauge inches to mm Conversion Chart

Stainless Steel Gauge Number	inches	mm
8	0.17187	4.365
9	0.15625	3.968
10	0.14062	3.571
11	0.125	3.175
12	0.10937	2.778
14	0.07812	1.984
16	0.0625	1.587
18	0.05	1.27
20	0.0375	0.9525
22	0.03125	0.7937
24	0.025	0.635
26	0.01875	0.476
28	0.01562	0.396
30	0.0125	0.3175

Aluminum Gauge inches to mm Conversion Chart

Aluminum Gauge Number	inches	mm
3	5.8268	5.8268
4	5.1892	5.1892
5	4.6203	4.6203
6	4.1148	4.1148
7	3.6652	3.6652
8	3.2639	3.2639
9	2.9058	2.9058
10	2.5883	2.5883
11	2.3038	2.3038
12	2.0523	2.0523
13	1.8288	1.8288
14	1.6281	1.6281
15	1.4503	1.4503
16	1.2903	1.2903
17	1.1506	1.1506
18	1.0236	1.0236
19	0.9119	0.9119
20	0.8128	0.8128
21	0.7239	0.7239
22	0.6426	0.6426
23	0.574	0.574
24	0.5105	0.5105
25	0.4547	0.4547
26	0.4039	0.4039
27	0.3607	0.3607
28	0.32	0.32
29	0.287	0.287
30	0.254	0.254
31	0.2261	0.2261
32	0.2032	0.2032
33	0.1803	0.1803
34	0.16	0.16
35	0.1422	0.1422

Mild Steel Gauge inches to mm Conversion Chart

Mild steel Gauge Number	inches	mm
3	0.2391	6.0731
4	0.2242	5.6947
5	0.2092	5.3137
6	0.1943	4.9352
7	0.1793	4.5542
8	0.1644	4.1758
9	0.1495	3.7973
10	0.1345	3.4163
11	0.1196	3.0378
12	0.1046	2.6568
13	0.0897	2.2784
14	0.0747	1.8974
15	0.0673	1.7094
16	0.0598	1.5189
17	0.0538	1.3665
18	0.0478	1.2141
19	0.0418	1.0617
20	0.0359	0.9119
21	0.0329	0.8357
22	0.0299	0.7392
23	0.0269	0.6833
24	0.0239	0.6071
25	0.0209	0.5309
26	0.0179	0.4547
27	0.0164	0.4166
28	0.0149	0.3785
29	0.035	0.3429
30	0.012	0.3048
31	0.0105	0.2667
32	0.0097	0.2464
33	0.009	0.2286
34	0.0082	0.2083
35	0.0075	0.1905
36	0.0067	0.1702

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