SHEET METAL GAUGE CHART: HOW THICK IS STEEL, GALVANIZED, STAINLESS, AND ALUMINUM?
Sheet metal gauge is a number, not a measurement, and it runs backwards: the higher the gauge, the thinner the sheet. It's also different for each material. 16 gauge carbon steel is about 0.060 inches thick, 16 gauge galvanized is a little thicker, and 16 gauge aluminum is about 0.051 inches.
That's why the chart below lists each material separately, and why drawings for anything critical should call out decimal thickness rather than gauge alone.
Published October 6, 2026 · JMC Fabrication
GAUGE CARBON STEEL GALVANIZED STAINLESS ALUMINUM 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 14 0.0747 0.0785 0.0781 0.0641 16 0.0598 0.0635 0.0625 0.0508 18 0.0478 0.0516 0.0500 0.0403 20 0.0359 0.0396 0.0375 0.0320 22 0.0299 0.0336 0.0312 0.0253 24 0.0239 0.0276 0.0250 0.0201 26 0.0179 0.0217 0.0187 0.0159 Carbon steel: Manufacturers' Standard Gauge. Galvanized: galvanized sheet gauge, including coating. Aluminum: Brown & Sharpe (AWG). Nominal values; actual sheet varies within mill tolerance.
Gauge numbers started as a way to describe sheet by weight per square foot, not by thickness. Each material grew its own table over time. Carbon steel uses the Manufacturers' Standard Gauge. Galvanized sheet has its own table that runs slightly thicker because it includes the zinc coating. Stainless is commonly listed on a table close to the old U.S. Standard gauge. Aluminum and other nonferrous metals use the Brown & Sharpe system, which runs noticeably thinner at the same number.
In practice, that means swapping materials without checking thickness can quietly change a part. Moving a 16 gauge steel cover to 16 gauge aluminum doesn't just make it lighter, it makes it about 15% thinner too.
Gauge is used for sheet. Once material reaches about 3/16 inch (0.1875) it's usually called plate and specified in fractions or decimals instead. Aluminum is often specified in decimals even in sheet thicknesses, such as 0.040, 0.063, 0.080, and 0.125, and it's worth matching how your drawings call it out to how the material is actually ordered.
- HVAC duct — Commercial galvanized duct usually falls somewhere between 26 and 18 gauge. The exact gauge isn't a preference, it comes from the SMACNA construction tables based on the duct's size, pressure class, and reinforcement spacing. Industrial and welded process duct runs heavier, often 16 gauge down into 10 gauge and plate.
- Covers, guards, and enclosures — Usually driven by stiffness and handling. Thinner sheet with formed flanges or ribs can often do the job of thicker flat sheet at less weight and cost.
- Brackets and supports — Driven by load. These are often 12 gauge or heavier, or plate, and are worth sizing by calculation rather than habit.
- Marine and coastal parts — Material choice matters as much as gauge. Aluminum and stainless are common for corrosion resistance, and since aluminum runs thinner at the same gauge, designs moving from steel to aluminum often step up a gauge or two to keep stiffness.
Gauge is shorthand, and the shorthand changes with the material. Use the chart to translate, and put decimal thickness on any drawing where the number really matters.
JMC Fabrication's Pascagoula, MS sheet metal shop cuts, brakes, and folds galvanized, carbon steel, stainless, and aluminum sheet every day, from SMACNA duct to custom formed parts for contractors across the Gulf Coast. Send a drawing and we'll confirm the material and thickness before anything gets cut.
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