Sheet Metal Gauge Chart: Steel and Aluminum Thickness in Inches and mmGauge-to-thickness reference for fabrication, machining, and supplier checks

Use this sheet metal gauge chart to compare common gauge numbers with approximate thickness in inches and millimeters for steel and aluminum. Gauge values are material-specific, so a 16 gauge steel sheet is not always the same thickness as a 16 gauge aluminum sheet. Treat the chart as a planning reference before confirming the exact material specification with your supplier or engineering standard.

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Steel & Aluminum

Compare gauge thickness by material instead of assuming one universal gauge value.

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Inch and Metric

Show decimal inch and millimeter equivalents for fabrication and mixed-unit drawings.

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Shop-Floor Reference

Use for estimates, RFQs, cutting plans, and supplier discussions before final verification.

Answer first: gauge is material-specific

Sheet metal gauge is a material-specific thickness reference. Lower gauge numbers usually mean thicker sheet, while higher gauge numbers mean thinner sheet. Use the steel or aluminum column that matches your material, then confirm the exact thickness, tolerance, alloy, coating, and supplier datasheet before ordering or releasing a design.

Search, Filter & Export

Showing 27 gauge rows. On small screens, swipe the table horizontally to see all columns.

Sheet metal gauge to inch and mm chart

Gauge values are material-specific. Use the steel or aluminum column that matches the drawing, RFQ, or supplier listing.

Gauge ↑	Steel (in)	Steel (mm)	Aluminum (in)	Aluminum (mm)	Approx. calculated weight note
10 ga	0.1345	3.416	0.1019	2.588	Steel 5.487 lb/ft²; aluminum 1.431 lb/ft², calculated from nominal density.
11 ga	0.1196	3.038	0.0907	2.304	Steel 4.879 lb/ft²; aluminum 1.273 lb/ft², calculated from nominal density.
12 ga	0.1046	2.657	0.0808	2.052	Steel 4.267 lb/ft²; aluminum 1.134 lb/ft², calculated from nominal density.
13 ga	0.0897	2.278	0.0720	1.829	Steel 3.659 lb/ft²; aluminum 1.011 lb/ft², calculated from nominal density.
14 ga	0.0747	1.897	0.0641	1.628	Steel 3.047 lb/ft²; aluminum 0.900 lb/ft², calculated from nominal density.
15 ga	0.0673	1.709	0.0571	1.450	Steel 2.746 lb/ft²; aluminum 0.802 lb/ft², calculated from nominal density.
16 ga	0.0598	1.519	0.0508	1.290	Steel 2.440 lb/ft²; aluminum 0.713 lb/ft², calculated from nominal density.
17 ga	0.0538	1.367	0.0453	1.151	Steel 2.195 lb/ft²; aluminum 0.636 lb/ft², calculated from nominal density.
18 ga	0.0478	1.214	0.0403	1.024	Steel 1.950 lb/ft²; aluminum 0.566 lb/ft², calculated from nominal density.
19 ga	0.0418	1.062	0.0359	0.912	Steel 1.705 lb/ft²; aluminum 0.504 lb/ft², calculated from nominal density.
20 ga	0.0359	0.912	0.0320	0.813	Steel 1.465 lb/ft²; aluminum 0.449 lb/ft², calculated from nominal density.
21 ga	0.0329	0.836	0.0285	0.724	Steel 1.342 lb/ft²; aluminum 0.400 lb/ft², calculated from nominal density.
22 ga	0.0299	0.759	0.0253	0.643	Steel 1.220 lb/ft²; aluminum 0.355 lb/ft², calculated from nominal density.
23 ga	0.0269	0.683	0.0226	0.574	Steel 1.097 lb/ft²; aluminum 0.317 lb/ft², calculated from nominal density.
24 ga	0.0239	0.607	0.0201	0.511	Steel 0.975 lb/ft²; aluminum 0.282 lb/ft², calculated from nominal density.
25 ga	0.0209	0.531	0.0179	0.455	Steel 0.853 lb/ft²; aluminum 0.251 lb/ft², calculated from nominal density.
26 ga	0.0179	0.455	0.0159	0.404	Steel 0.730 lb/ft²; aluminum 0.223 lb/ft², calculated from nominal density.
27 ga	0.0164	0.417	0.0142	0.361	Steel 0.669 lb/ft²; aluminum 0.199 lb/ft², calculated from nominal density.
28 ga	0.0149	0.378	0.0126	0.320	Steel 0.608 lb/ft²; aluminum 0.177 lb/ft², calculated from nominal density.
29 ga	0.0135	0.343	0.0113	0.287	Steel 0.551 lb/ft²; aluminum 0.159 lb/ft², calculated from nominal density.
30 ga	0.0120	0.305	0.0100	0.254	Steel 0.490 lb/ft²; aluminum 0.140 lb/ft², calculated from nominal density.
31 ga	0.0105	0.267	0.0089	0.226	Steel 0.428 lb/ft²; aluminum 0.125 lb/ft², calculated from nominal density.
32 ga	0.0097	0.246	0.0080	0.203	Steel 0.396 lb/ft²; aluminum 0.112 lb/ft², calculated from nominal density.
33 ga	0.0090	0.229	0.0071	0.180	Steel 0.367 lb/ft²; aluminum 0.100 lb/ft², calculated from nominal density.
34 ga	0.0082	0.208	0.0063	0.160	Steel 0.335 lb/ft²; aluminum 0.088 lb/ft², calculated from nominal density.
35 ga	0.0075	0.190	0.0056	0.142	Steel 0.306 lb/ft²; aluminum 0.079 lb/ft², calculated from nominal density.
36 ga	0.0067	0.170	0.0050	0.127	Steel 0.273 lb/ft²; aluminum 0.070 lb/ft², calculated from nominal density.

Formula:mm = inch × 25.4

Weight:approx lb/ft² = thickness_in × density_lb/in³ × 144

Last reviewed:2026-07-05

How to use this sheet metal gauge chart

Choose the material column: steel or aluminum.
Find the gauge number from the drawing, RFQ, or supplier listing.
Read the decimal inch and millimeter thickness for that material.
If the part is weight-sensitive, confirm the alloy density and coating before using weight estimates.
For final design, purchasing, or inspection, verify the value against the applicable material standard and supplier datasheet.

Why steel and aluminum gauge thickness can differ

Gauge is not a universal thickness unit. The same gauge number can map to different thicknesses depending on material family and reference table. This is why the chart separates steel and aluminum instead of showing one generic gauge-to-mm value.

Common sheet metal gauge examples

10 gauge sheet metal

thick sheet used when stiffness or durability matters. Steel is 0.1345 in / 3.416 mm; aluminum is 0.1019 in / 2.588 mm.

Confirm material before ordering

16 gauge sheet metal

common for brackets, panels, enclosures, and fabrication planning. Steel is 0.0598 in / 1.519 mm; aluminum is 0.0508 in / 1.290 mm.

Confirm material before ordering

20 gauge sheet metal

often used for lighter panels or covers. Steel is 0.0359 in / 0.912 mm; aluminum is 0.0320 in / 0.813 mm.

Confirm material before ordering

Weight, alloy, coating, and tolerance notes

The weight values shown in the chart are approximate calculated weight, not certified supplier weight. They use the formula approx lb/ft² = thickness_in × density_lb/in³ × 144 with nominal density assumptions: steel 0.2833 lb/in³ nominal sheet steel density; aluminum 0.0975 lb/in³ nominal aluminum density.

Actual sheet weight can change with alloy, coating, temper, tolerance, and supplier-specific material specifications.

Before using gauge thickness for design or purchasing

Sheet metal gauge values can vary by material family, alloy, coating, supplier table, and manufacturing tolerance. Do not use this chart as the only authority for structural design, pressure-retaining parts, safety-critical assemblies, or certified material purchasing. Always confirm the exact thickness, tolerance, temper, coating, and weight with the drawing, applicable standard, and supplier documentation.

Data sources and calculation assumptions

Thickness sources: Cross-checked against multiple publicly available online reference charts and normalized for consistent inch-to-millimeter conversion.
Last reviewed: 2026-07-05.
Millimeter formula: mm = inch × 25.4.
Weight note: Thickness values are cross-checked against public gauge reference tables; weight is calculated from thickness and nominal material density, not a certified purchasing weight.

Sheet Metal Gauge FAQ

What is a sheet metal gauge chart?

A sheet metal gauge chart maps gauge numbers to material thickness in inches and millimeters. The value depends on the material, so steel and aluminum should be checked in separate columns.

Does a lower gauge number mean thicker sheet metal?

Yes. In common sheet metal gauge tables, lower gauge numbers usually mean thicker sheet, while higher gauge numbers mean thinner sheet. Always confirm the material-specific chart before using a value.

Is 16 gauge steel the same thickness as 16 gauge aluminum?

No. Gauge is material-specific, so 16 gauge steel and 16 gauge aluminum can have different thickness values. Use the steel column for steel sheet and the aluminum column for aluminum sheet.

Can I use gauge thickness for final engineering design?

Use gauge thickness as a preliminary reference only. Final design, inspection, and procurement should confirm the exact thickness, tolerance, alloy, coating, and supplier specification.

Why does the chart show both inches and millimeters?

Many drawings, RFQs, and supplier catalogs mix inch gauge references with metric manufacturing requirements. Showing both units helps engineers and buyers compare sheet thickness without doing a separate conversion.

Should sheet metal weight be calculated from gauge alone?

No. Weight depends on thickness, material density, alloy, coating, and sheet size. Gauge can help estimate thickness, but final weight should be calculated from confirmed material data.

Which material should I choose in the chart?

Choose the column that matches the sheet material in your drawing, RFQ, or supplier quote. If the material is not specified, do not assume steel and aluminum gauge values are interchangeable.