Sheet Metal Gauge Thickness Chart: mm and inch
Engineering Team | Anjue Metal | Updated Nov 6, 2026 | 7 min read
On sheet metal, a bigger gauge number means a thinner sheet - which confuses almost everyone the first time. This chart converts the common US steel gauges into millimetres and inches, and then gives the one caveat that prevents costly mix-ups: gauge-to-thickness is not the same across materials.
1. The gauge to thickness chart
These values are for carbon steel using the Manufacturers' Standard Gauge (MSG). Gauge is inverse: 3 gauge is a thick ~6 mm plate, 24 gauge is a thin ~0.6 mm sheet.
| Gauge | Thickness (mm) | Thickness (inch) |
|---|---|---|
| 3 | 6.07 | 0.239 |
| 4 | 5.70 | 0.224 |
| 6 | 4.94 | 0.194 |
| 7 | 4.55 | 0.179 |
| 8 | 4.18 | 0.164 |
| 10 | 3.42 | 0.135 |
| 11 | 3.04 | 0.120 |
| 12 | 2.66 | 0.105 |
| 14 | 1.90 | 0.075 |
| 16 | 1.52 | 0.060 |
| 18 | 1.21 | 0.048 |
| 20 | 0.91 | 0.036 |
| 22 | 0.76 | 0.030 |
| 24 | 0.61 | 0.024 |
| 26 | 0.46 | 0.018 |
Read it as: for a given gauge, the millimetre and inch thickness are fixed for that material system. The trap is assuming the same gauge means the same thickness in aluminum or stainless - it does not (see below).
2. Steel vs aluminum vs stainless gauge
Gauge numbering is material-specific. Carbon steel uses the MSG system above. Aluminum uses the AWG/Brown and Sharpe scale, where the same gauge number maps to a different thickness. Stainless steel has its own gauge conventions too. The practical rule: never specify a part by gauge alone when more than one material is in play - state the actual millimetre (or inch) thickness.
3. Typical enclosure thicknesses by application
As a starting point for sheet metal enclosures:
- Small indoor control panels / junction boxes: 1.2-1.5 mm steel (about 18-16 gauge).
- Outdoor telecom and power cabinets (small): 1.5-2.0 mm steel (16-14 gauge).
- Large floor-standing cabinets and frames: 2.0-3.0 mm steel (14-11 gauge) for rigidity.
- Aluminum enclosures: often 2.0-3.0 mm, because aluminum is weaker per millimetre than steel and needs more section to carry the same load.
4. How to specify thickness on a drawing
Put the actual dimension on the drawing - for example "material: cold-rolled steel, 2.0 mm" - and treat gauge only as a colloquial shorthand in conversation. That single habit removes the most common enclosure mismatch: a supplier quoting 14 gauge in steel and you expecting 14 gauge in aluminum, which are not the same plate.
Frequently Asked Questions
Frequently Asked QuestionsThinner. On the standard steel scale, 3 gauge is about 6 mm thick while 24 gauge is about 0.6 mm. The number runs opposite to the thickness, which is why it trips people up.
No. Gauge-to-thickness is material-specific: carbon steel (MSG), aluminum (AWG/B&S) and stainless each map the same gauge number to a different actual thickness. State the millimetre value to avoid ambiguity.
Typically 1.5-2.0 mm (16-14 gauge) for small outdoor cabinets, and 2.0-3.0 mm (14-11 gauge) for large floor-standing cabinets. Aluminum versions usually need 2.0-3.0 mm for equivalent stiffness.
Millimetres (or inches). Gauge is useful in conversation but ambiguous across materials; the drawing should carry the actual thickness so supplier and buyer measure the same thing.
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