Sheet Metal Gauge Chart — Steel, Stainless, Aluminum & Galvanized Thickness

Sheet metal gauge chart 7–30: decimal-inch and millimetre thickness for standard steel (MSG), galvanized, stainless, and aluminum (Brown & Sharpe).

Updated August 18, 2026

A gauge number is not one thickness — it is four. Each sheet-metal material carries its own gauge system, so 16 gauge means 0.0598 in for standard steel, 0.0635 in for galvanized, 0.0625 in for stainless, and only 0.0508 in for aluminum. Steel uses the Manufacturers’ Standard Gauge (MSG), derived from a weight basis of 41.82 lb per square foot per inch of thickness; galvanized sheet adds a 0.0037 in zinc-coating allowance to every MSG thickness; stainless follows its own gauge; and aluminum keeps the Brown & Sharpe (B&S) wire-gauge system — the same geometric progression as AWG electrical wire.

In every system the number runs opposite to the thickness: higher gauge, thinner sheet, a relic of gauge numbers counting wire-drawing passes. There is no galvanized gauge 7 — published galvanized tables start at gauge 8, so that cell is left blank rather than extrapolated. The inch values below are the standard published decimal equivalents, adjudicated across multiple independent supplier and standards charts; the millimetre table is computed from them at exactly 25.4 mm per inch. For flat-pattern bend math with these thicknesses, the bend allowance calculator takes the decimal thickness directly.

Gauge Thickness — Decimal Inches

Gauge	Steel MSG (in)	Galvanized (in)	Stainless (in)	Aluminum B&S (in)
7	0.1793	—	0.1875	0.1443
8	0.1644	0.1681	0.1719	0.1285
9	0.1495	0.1532	0.1563	0.1144
10	0.1345	0.1382	0.1406	0.1019
11	0.1196	0.1233	0.1250	0.0907
12	0.1046	0.1084	0.1094	0.0808
13	0.0897	0.0934	0.0938	0.0720
14	0.0747	0.0785	0.0781	0.0641
15	0.0673	0.0710	0.0703	0.0571
16	0.0598	0.0635	0.0625	0.0508
17	0.0538	0.0575	0.0563	0.0453
18	0.0478	0.0516	0.0500	0.0403
19	0.0418	0.0456	0.0438	0.0359
20	0.0359	0.0396	0.0375	0.0320
21	0.0329	0.0366	0.0344	0.0285
22	0.0299	0.0336	0.0313	0.0253
23	0.0269	0.0306	0.0281	0.0226
24	0.0239	0.0276	0.0250	0.0201
25	0.0209	0.0247	0.0219	0.0179
26	0.0179	0.0217	0.0188	0.0159
27	0.0164	0.0202	0.0172	0.0142
28	0.0149	0.0187	0.0156	0.0126
29	0.0135	0.0172	0.0141	0.0113
30	0.0120	0.0157	0.0125	0.0100

Steel = Manufacturers’ Standard Gauge; galvanized = MSG + 0.0037 in zinc allowance (ASTM A653 practice, no gauge 7 published); stainless cells are the standard 4-decimal renderings of exact fractions (13 ga = 0.09375 in); aluminum = Brown & Sharpe (AWG).

Gauge Thickness — Millimetres (computed)

Gauge	Steel MSG (mm)	Galvanized (mm)	Stainless (mm)	Aluminum B&S (mm)
7	4.554	—	4.762	3.665
8	4.176	4.270	4.366	3.264
9	3.797	3.891	3.970	2.906
10	3.416	3.510	3.571	2.588
11	3.038	3.132	3.175	2.304
12	2.657	2.753	2.779	2.052
13	2.278	2.372	2.383	1.829
14	1.897	1.994	1.984	1.628
15	1.709	1.803	1.786	1.450
16	1.519	1.613	1.587	1.290
17	1.367	1.460	1.430	1.151
18	1.214	1.311	1.270	1.024
19	1.062	1.158	1.113	0.912
20	0.912	1.006	0.952	0.813
21	0.836	0.930	0.874	0.724
22	0.759	0.853	0.795	0.643
23	0.683	0.777	0.714	0.574
24	0.607	0.701	0.635	0.511
25	0.531	0.627	0.556	0.455
26	0.455	0.551	0.478	0.404
27	0.417	0.513	0.437	0.361
28	0.378	0.475	0.396	0.320
29	0.343	0.437	0.358	0.287
30	0.305	0.399	0.318	0.254

Computed cells: mm = 25.4 × the decimal-inch value in the table above, shown to 3 decimals.

Sources & Further Reading

Manufacturers’ Standard Gauge for steel sheet (41.82 lb/ft² per inch weight basis) and Galvanized Sheet Gauge per ASTM A653 practice — published gauge tables
MachineMfg five-decimal gauge chart (primary adjudicator), cross-checked against sheetmetal.me, CNC Cookbook, Metal Supermarkets, and Welders Supply published charts (≥3 independent confirmations per material)
Aluminum: Brown & Sharpe / AWG gauge, t = 0.005 × 92^((36−n)/39) in — published values match the formula at every gauge

Frequently Asked Questions

Why does 16 gauge steel differ from 16 gauge aluminum?

They come from different gauge systems. Steel sheet uses the Manufacturers’ Standard Gauge, defined from a weight of 41.82 lb/ft² per inch of thickness, while aluminum kept the older Brown & Sharpe wire gauge, a geometric progression. At gauge 16 that is 0.0598 in of steel versus 0.0508 in of aluminum — an 18% difference — so a gauge number without the material named is ambiguous.

Is a higher gauge number thicker or thinner?

Thinner. Gauge numbers descend as thickness grows in every sheet-metal system: 10 gauge steel is 0.1345 in but 20 gauge is 0.0359 in. The convention traces back to wire gauges counting drawing passes — more passes, thinner wire — and sheet gauges inherited it.

Why is galvanized sheet thicker than plain steel at the same gauge?

The galvanized sheet gauge includes the zinc coating: every galvanized thickness is the MSG steel thickness plus a 0.0037 in coating allowance, so 16 gauge galvanized is 0.0598 + 0.0037 = 0.0635 in. The base steel inside is the same 16 gauge MSG thickness.

What gauge is 1/8 inch thick?

Closest matches: 11 gauge steel (0.1196 in) runs just under 1/8 in (0.125 in), while 11 gauge stainless is exactly 0.125 in and 8 gauge aluminum (0.1285 in) just over. Above roughly 3/16 in, material is normally specified as plate in decimal inches rather than by gauge.

Try the Calculators

Bend Allowance Calculator — K-Factor, Bend Deduction & Flat Pattern Metal Weight Calculator — Steel, Aluminum, Plate, Bar & Tube

Sheet Metal Gauge Chart — Steel, Stainless, Aluminum & Galvanized Thickness — reuven.tools/reference/sheet-metal-gauges — verified against: Manufacturers’ Standard Gauge for steel sheet (41.82 lb/ft² per inch weight basis) and Galvanized Sheet Gauge per ASTM A653 practice — published gauge tables; MachineMfg five-decimal gauge chart (primary adjudicator), cross-checked against sheetmetal.me, CNC Cookbook, Metal Supermarkets, and Welders Supply published charts (≥3 independent confirmations per material); Aluminum: Brown & Sharpe / AWG gauge, t = 0.005 × 92^((36−n)/39) in — published values match the formula at every gauge