Key Takeaways

• "Gauge" is an imperial system — Australian metalworkers use millimetres (mm) for sheet thickness.
• Higher gauge numbers mean thinner sheet (counterintuitive — 16ga is thicker than 18ga).
• Gauge standards differ between steel and aluminium — always specify mm to avoid confusion.
• For laser cutting in Australia, always specify thickness in mm, not gauge.

Sheet Metal Gauge Thickness in Australia: The Complete mm Guide

If you've ordered sheet metal in the United States or worked with American manufacturing specs, you've likely encountered gauge numbers: 16ga, 18ga, 20ga. In Australia, the metal industry uses millimetres (mm) for sheet thickness — and for good reason. Gauge numbers are ambiguous, vary between materials, and have no place in a modern CNC workflow. This guide explains gauge systems, provides conversion tables, and explains why every Australian laser cutting order should specify thickness in mm.

What Is Sheet Metal Gauge?

Gauge (or gage) is a legacy imperial system for specifying sheet metal thickness. It originated in the wire drawing industry and was adopted for sheet metal in the 19th century. The key quirks:

• Higher gauge = thinner sheet. 18 gauge is thinner than 16 gauge.
• Gauge numbers are not universal. 16 gauge mild steel and 16 gauge aluminium are different thicknesses.
• There is no simple formula. The gauge-to-mm relationship is defined by industry tables, not equations.

Sheet Metal Gauge to mm Conversion Table: Mild Steel

Sheet Metal Gauge to mm Conversion Table: Aluminium

Why Australian Laser Cutting Uses mm, Not Gauge

Australia has used metric units since metrication in the 1970s. Sheet metal is manufactured, stocked, and sold in metric thicknesses. The standard sheet sizes are 2400x1200mm and 3000x1500mm. Material certs list thickness in mm. Purchase orders specify mm.

For laser cutting specifically:

• Laser cutting software (nesting, CAM) uses mm
• Cutting parameters (speed, power, focus) are calibrated to exact mm thicknesses
• Tolerance specifications (±0.1mm) are meaningless in gauge
• Quoting platforms price by material thickness in mm

If you receive an American spec sheet that calls for 16ga mild steel, convert to 1.6mm for your Australian laser cutting order.

Common Australian Laser Cut Thicknesses

The most commonly ordered sheet metal thicknesses for laser cutting in Australia are:

• Mild steel: 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm
• Stainless 304: 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm, 6mm
• Aluminium 5005H34: 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm, 6mm

Ferracut stocks all these thicknesses for instant online ordering. Select your material and thickness in the quote tool — all specified in mm.

Tips for Working With Both Systems

If you work with both Australian and American suppliers or use American fabrication guides:

• Always confirm units before ordering — ask for mm thickness if gauge is specified
• Use a conversion table (above) to find the nearest Australian stock thickness
• Round to the nearest available stock size — 1.59mm (16ga steel) rounds to 1.6mm or 1.5mm
• Update imported drawings to mm before uploading for laser cutting quotes

Get Your Parts Cut Today

Ready to order? Upload your DXF to Ferracut and select your material thickness in mm. Instant quote, no minimum order, Australia-wide delivery.