What is a sheet metal gauge?

A gauge is a standard number describing sheet thickness. It is a reverse scale — higher numbers are thinner. Different materials use different gauge systems, so the same gauge number gives a different thickness for steel, galvanized steel, stainless steel and aluminum.

What are the standard gauges for sheet steel?

Common fabrication gauges run from 7 (0.1793 in) to 30 (0.0126 in). The most widely used are 10 (0.1345 in), 12 (0.1046 in), 14 (0.0747 in), 16 (0.0598 in), 18 (0.0478 in) and 20 (0.0359 in) in standard steel.

Which is thicker, 14 gauge or 16 gauge sheet metal?

14 gauge is thicker. In standard steel, 14 gauge is 0.0747 in (1.897 mm) and 16 gauge is 0.0598 in (1.518 mm).

What is thicker, 18 or 20 gauge?

18 gauge is thicker. In standard steel, 18 gauge is 0.0478 in (1.214 mm) and 20 gauge is 0.0359 in (0.911 mm) — about 33% thicker.

Is 16 gauge steel strong enough for a trailer?

It depends on the structure and span. 16 gauge standard steel is 0.0598 in (1.518 mm). For load-bearing applications, thickness alone is not the deciding factor — section geometry, bracing and span matter more. Consult the trailer manufacturer's specification.

Sheet Metal Gauge Chart

Gauge number to thickness for standard steel, galvanized steel, stainless steel, aluminum and copper — in inches and millimeters, with a gauge converter and the thickness formula.

Quick Answer

Gauge

Material

Sheet Metal Gauge Thickness Chart

Gauge^[3]	Standard steel in^[3]	Standard steel mm^[2]	Galvanized in^[4]	Galvanized mm^[2]	Stainless in^[5]	Stainless mm^[2]	Aluminum in^[1]	Aluminum mm^[2]
6 gauge #	—	—	—	—	—	—	0.1620	4.115
7 gauge #	0.1793	4.554	—	—	—	—	0.1443	3.665
8 gauge #	0.1644	4.176	0.1681	4.270	0.1719	4.366	0.1285	3.264
9 gauge #	0.1495	3.797	0.1532	3.891	0.1563	3.970	0.1144	2.906
10 gauge #	0.1345	3.416	0.1382	3.510	0.1406	3.571	0.1019	2.588
11 gauge #	0.1196	3.038	0.1233	3.132	0.1250	3.175	0.0907	2.304
12 gauge #	0.1046	2.657	0.1084	2.753	0.1094	2.779	0.0808	2.052
13 gauge #	0.0897	2.278	0.0934	2.372	0.0937	2.380	0.0720	1.829
14 gauge #	0.0747	1.897	0.0785	1.994	0.0781	1.984	0.0641	1.628
15 gauge #	0.0673	1.709	0.0710	1.803	0.0703	1.786	0.0571	1.450
16 gauge #	0.0598	1.519	0.0635	1.613	0.0625	1.587	0.0508	1.290
17 gauge #	0.0538	1.367	0.0575	1.460	0.0562	1.427	0.0453	1.151
18 gauge #	0.0478	1.214	0.0516	1.311	0.0500	1.270	0.0403	1.024
19 gauge #	0.0418	1.062	0.0456	1.158	0.0437	1.110	0.0359	0.912
20 gauge #	0.0359	0.912	0.0396	1.006	0.0375	0.952	0.0320	0.813
21 gauge #	0.0329	0.836	0.0366	0.930	0.0344	0.874	0.0285	0.724
22 gauge #	0.0299	0.759	0.0336	0.853	0.0312	0.792	0.0253	0.643
23 gauge #	0.0269	0.683	0.0306	0.777	0.0281	0.714	0.0226	0.574
24 gauge #	0.0239	0.607	0.0276	0.701	0.0250	0.635	0.0201	0.511
25 gauge #	0.0209	0.531	0.0247	0.627	0.0219	0.556	0.0179	0.455
26 gauge #	0.0179	0.455	0.0217	0.551	0.0187	0.475	0.0159	0.404
27 gauge #	0.0164	0.417	0.0202	0.513	0.0172	0.437	0.0142	0.361
28 gauge #	0.0149	0.378	0.0187	0.475	0.0156	0.396	0.0126	0.320
29 gauge #	0.0135	0.343	0.0172	0.437	0.0141	0.358	0.0113	0.287
30 gauge #	0.0126	0.320	0.0157	0.399	0.0125	0.318	0.0100	0.254

Thickness values follow the official gauge system for each material (Manufacturers' Standard for steel; US Standard for galvanized and stainless; Brown & Sharpe for aluminum). Values cross-checked against two independent published tables.

Gauge to mm / inch Converter

Material

Thickness (inch)

Thickness (mm)

Enter a thickness to find the nearest gauge.

How Gauge Relates to Thickness

Gauge is a reverse scale: a larger gauge number means a thinner sheet. 10 gauge is thicker than 20 gauge. The relationship is not linear and not the same across materials — that is why one gauge number maps to different physical thicknesses depending on what the sheet is made of.

For example, 16 gauge is:

0.0598 in (1.519 mm) in standard steel
0.0635 in (1.613 mm) in galvanized steel
0.0625 in (1.587 mm) in stainless steel
0.0508 in (1.290 mm) in aluminum

Why the difference? Gauge originated as a weight-per-area measure, not a direct thickness measure. Because steel, zinc-coated steel, stainless and aluminum have different densities, the same gauge number resolves to a different thickness for each. Always specify thickness in inches or millimeters on a drawing — never gauge alone.

Decimal, Fraction and Gauge

1/16 in = 0.0625 in = 1.588 mm, which sits between 16 gauge galvanized (0.0635 in) and 16 gauge stainless (0.0625 in). This is why fabricators convert fraction to decimal before choosing a gauge — see the fraction to decimal chart.

Frequently Asked Questions

What is a sheet metal gauge?: A gauge is a standard number describing sheet thickness. It is a reverse scale — higher numbers are thinner. Different materials use different gauge systems, so the same gauge number gives a different thickness for steel, galvanized steel, stainless steel and aluminum.
What are the standard gauges for sheet steel?: Common fabrication gauges run from 7 (0.1793 in) to 30 (0.0126 in). The most widely used are 10 (0.1345 in), 12 (0.1046 in), 14 (0.0747 in), 16 (0.0598 in), 18 (0.0478 in) and 20 (0.0359 in) in standard steel.
Which is thicker, 14 gauge or 16 gauge sheet metal?: 14 gauge is thicker. In standard steel, 14 gauge is 0.0747 in (1.897 mm) and 16 gauge is 0.0598 in (1.518 mm).
What is thicker, 18 or 20 gauge?: 18 gauge is thicker. In standard steel, 18 gauge is 0.0478 in (1.214 mm) and 20 gauge is 0.0359 in (0.911 mm) — about 33% thicker.
Is 16 gauge steel strong enough for a trailer?: It depends on the structure and span. 16 gauge standard steel is 0.0598 in (1.518 mm). For load-bearing applications, thickness alone is not the deciding factor — section geometry, bracing and span matter more. Consult the trailer manufacturer's specification.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	Brown & Sharpe (US Standard) Gage for aluminium, copper and brass	standard	n/a — industry convention
[2]	Millimetre conversion	derived	Inch values × 25.4, rounded to 3 decimal places.
[3]	Manufacturers' Standard Gage for Sheet Steel	standard	n/a — industry convention, pre-1930 origin
[4]	US Standard Gage for galvanized (zinc-coated) sheet	standard	n/a — industry convention
[5]	US Standard Gage for stainless steel sheet	standard	n/a — industry convention

Data Sources

Standard	Revision	What it covers on this page
Manufacturers' Standard Gage for Sheet Steel	n/a — industry convention, pre-1930 origin	standard steel and galvanized sheet thickness by gauge
Brown & Sharpe (US Standard) Gage	n/a — industry convention	aluminium, copper and brass sheet thickness by gauge

Cross-checked against:

Metal Supermarkets published sheet metal gauge chart
Engineers Edge sheet metal & wire gauge table

Nominal values as published in the referenced standard. Manufacturing tolerances apply.

Accuracy and use. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Sheet Metal Gauge Chart." https://refmanual.com/charts/sheet-metal-gauge/ (accessed 2026-09-29). Data from Manufacturers' Standard Gage for Sheet Steel, n/a — industry convention, pre-1930 origin.

BibTeX

@misc{sheet-metal-gauge,
  title        = {Sheet Metal Gauge Chart},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/charts/sheet-metal-gauge/}},
  note         = {Accessed: 2026-09-29},
  source       = {Manufacturers' Standard Gage for Sheet Steel, n/a — industry convention, pre-1930 origin}
}

RIS (EndNote, Zotero, Mendeley)

TY  - ELEC
TI  - Sheet Metal Gauge Chart
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/charts/sheet-metal-gauge/
PY  - 2026
DA  - 2026-09-29
N1  - Source: Manufacturers' Standard Gage for Sheet Steel, n/a — industry convention, pre-1930 origin
ER  -

Each row in the tables above also has a permanent link — hover a row and use the # link to cite a single value rather than the whole page.