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Tools / Gauge & thickness chart

Sheet-metal reference

Sheet metal gauge to thickness chart

Convert sheet-metal gauge to material thickness in millimetres and inches. Standard (uncoated) steel, galvanized steel, aluminium and stainless steel each use a different gauge standard — pick the material and filter by gauge.

Gauge Thickness (mm) Thickness (in)

From gauge to flat pattern

Know your thickness? Bendline takes a 3D STEP part and unfolds it to a cut-ready DXF in your browser — set the material thickness and download the blank.

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How sheet-metal gauge works

Gauge is a legacy numbering system for sheet thickness: the higher the gauge number, the thinner the material. Confusingly, the same gauge number means a different thickness depending on the metal, because steel, galvanized steel, aluminium and stainless each follow a different published standard. Always convert gauge to an actual thickness before you set up tooling or cut a blank.

Which standard is which

Standard steel uses the US Manufacturers' Standard Gauge for uncoated sheet. Galvanized steel is slightly thicker for the same gauge number because the figure includes the zinc coating. Aluminium is normally specified by the Brown & Sharpe (American Wire Gauge) system. Stainless steel has its own gauge standard, close to but not identical to carbon steel. This chart lists all four.

Working in mm

Outside North America, thickness is usually called out directly in millimetres — 1.0, 1.5, 2.0, 3.0 mm and so on. Those preferred metric thicknesses don't map exactly to gauge numbers, so this table shows both the mm and inch equivalents to bridge drawings from either convention. Once you have the thickness, feed it into the K-factor and flat-length calculators.