Higher gauge number, thinner sheet — and the number means something different in every metal.
Every gauge from 3 to 30, converted to inches and millimeters for aluminum, mild steel, stainless, and galvanized sheet. Cross-sections are drawn to scale so you can see the difference, not just read it. Click any gauge for a DFM Preflight against our real TRUMPF bend tooling — and every thickness marked in green is priced instantly online.
Every gauge we can reference, in every metal we run — all priced instantly online. Green chips mark the real decimal thickness we hold closest to that gauge; click one for a DFM Preflight with our actual TRUMPF bend tooling data. Gauge values are nominal reference conversions per the standard named in each column header. Order to the decimal thickness, not the gauge number.
| Gauge Number | Aluminum B&S · ASTM B209 | Mild Steel MSG · A1008 / A1011 | Stainless MSG SS · ASTM A240 | Galvanized MSG Galv · ASTM A653 |
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Gauge thicknesses are nominal reference values from the published standard for each metal. Mill tolerance still applies — ASTM B209 for aluminum, A1008/A1011 for carbon steel, A480 for stainless, A653 for galvanized. Galvanized thicknesses include the zinc coating; the standard has no published gauge below 8. The green stock chips show the actual decimal thickness we hold, which is what we cut and what we quote.
Gauge is not one system. It is four systems that happen to share the same numbers, and aluminum is the outlier that catches people out.
Aluminum sheet is gauged on the Brown & Sharpe (AWG) scale. Carbon steel uses the Manufacturers’ Standard Gauge. They are not interchangeable, and the gap widens as the sheet gets thicker:
16 ga aluminum = 0.0508″ but 16 ga mild steel = 0.0598″ — an 18% difference in thickness, stiffness, and bend force.
When somebody says “16 gauge aluminum,” there is a good chance they mean 0.063″ — one-sixteenth of an inch, the aluminum sheet most shops keep on the rack. On the Brown & Sharpe scale, 0.063″ is 14 gauge, not 16.
The fix is simple: specify aluminum by decimal thickness. Put 0.063″ on the drawing and in the quote, never “16 ga.” Every aluminum SKU in our catalog carries its decimal thickness for exactly this reason, and the instant quote prices off the decimal. Where you see a gauge number next to an aluminum thickness on this site, treat it as a shop-floor shorthand, not a spec.
Numbers on a chart flatten out. Stack the gauges next to each other at true relative thickness — against a dime, a credit card, a sheet of paper — and the choice between 14 and 18 gauge stops being abstract.
Gauge is a trade between stiffness, weight, bend force, and cost. These bands are where most laser-cut sheet metal parts land. Thicknesses shown are mild steel — use the chart above to convert for your metal.
Frames, thick mounting plates, weld-on brackets, machine bases. Stiff enough to resist deflection under real load. Needs generous bend radii and serious tonnage.
Brackets, chassis, weldments, enclosures that take a knock. 14 gauge is the single most common gauge we cut — strong, formable, and still cheap to nest.
The starting point when you are not sure. Bends cleanly, holds a tapped thread with hardware, takes powder coat well, and keeps part weight down. Most electronics enclosures live here.
Lightweight covers, decorative panels, shields. Flexes under hand pressure, so add ribs, flanges, or hems for stiffness. Watch for oil-canning on large flat faces.
Shim stock, gaskets, EMI shielding, trim. Handling marks and laser-induced warping become the limiting factors long before strength does.
Design around a stocked thickness and your part cuts sooner and prices lower. Everything below is real catalog stock with real TRUMPF bend data behind it — listed by decimal thickness, because that is what the laser and the press brake see.
The questions we get asked most often about sheet metal gauge, thickness, and how to specify it so the part comes out the way you drew it.
18 ga steel = 0.0478″, 18 ga stainless = 0.0500″, and 18 ga aluminum = 0.0403″. Never carry a gauge number across metals — convert through the chart above, or better, specify the decimal.0.0598″ (1.52 mm) nominal. We stock A1008 cold-rolled and A36 hot-rolled at 0.060″, both live in the instant quote. In stainless, 16 gauge is 0.0625″ and we stock 0.060″. In aluminum, 16 gauge is 0.0508″ and we stock 0.050″. It is a good default for panels, covers, and light brackets.0.0747″ (1.90 mm) nominal; we stock 0.075″. It is the most-cut gauge in our shop because it balances three things at once: it resists deflection without ribs, it still air-bends to a tight inside radius, and it nests cheaply. If a 16 gauge part feels flimsy in your hand, 14 is the next stop.0.060″ (16 ga) if you want the gauge for human readers — but the decimal is what gets manufactured.0.060″) only clears both for a #4-40 in the inch series. The tap drill size chart checks every thread against a thickness you pick and tells you where to use self-clinching hardware instead.0.050″ stock. Click the chip for a full DFM Preflight on that SKU: tooling, radius, minimum flange, bend force, hardware and countersink feasibility, and sheet weight.