Blog · Specification
Aluminum sheet gauge chart: inches and millimeters
Gauge is a scale inherited from steel with no official equivalent for aluminum: 22 gauge is 0.0253 in on the most used chart, but varies by standard. That is why a mill specifies in decimal inches or millimeters with tolerance. Almexa makes coil and sheet from 0.008 to 0.134 in, circles from 0.018 to 0.157 in, fin stock from 0.0039 to 0.010 in and foil from 0.00035 in. Source: Almexa 2021 catalog; Brown & Sharpe gauge chart.
"I need 18 gauge sheet" is a common line on a quote request, and a frequent source of misunderstanding. This guide has the chart and explains why you should stop using it.
Where gauge comes from
Gauges date to the 19th century for steel wire and sheet, with different systems by country and metal. For aluminum, the chart most used in North America is Brown & Sharpe (AWG). No standard officially fixes gauge for aluminum; the same number can mean two different thicknesses depending on who reads it.
Gauge to decimal chart
| Gauge | Inches | Millimeters | Usual aluminum use |
|---|---|---|---|
| 8 | 0.1285 | 3.26 | Stamping plate, structures |
| 10 | 0.1019 | 2.59 | Cookware bases, truck boxes |
| 12 | 0.0808 | 2.05 | Bodies, tanks |
| 14 | 0.0641 | 1.63 | Stamped parts, brackets |
| 16 | 0.0508 | 1.29 | Heavy facades, panels |
| 18 | 0.0403 | 1.02 | General sheet, signage |
| 20 | 0.0320 | 0.81 | Ceilings, gutters, blinds |
| 22 | 0.0253 | 0.64 | Painted sheet, ducts |
| 24 | 0.0201 | 0.51 | Light facades, cladding |
| 26 | 0.0159 | 0.40 | Insulation, liners |
| 30 | 0.0100 | 0.25 | Heavy fin stock |
Values per the Brown & Sharpe chart; other charts differ in the second decimal.
Why order in decimal inches or millimeters
A mill rolls to a nominal thickness with a tolerance, for example 0.040 in ±0.0015. When you order "18 gauge", the sales executive has to guess whether you mean 0.0403, 0.040 or 0.047 in, and your stamping die does notice the difference. Order nominal thickness and tolerance in decimal inches or millimeters; gauge is only for conversation.
Ranges Almexa makes
| Product | Thickness | Approximate gauge |
|---|---|---|
| Coil and sheet | 0.008 to 0.134 in | 32 to 8 |
| Painted sheet | 0.018 to 0.049 in | 25 to 16 |
| Circles | 0.018 to 0.157 in | 25 to 6 |
| Fin stock | 0.0039 to 0.010 in | 38 to 30 |
| Foil | 0.00035 to 0.0024 in | Off the gauge scale |
How to choose thickness
- Flat facades and ceilings: 0.020 to 0.050 in; thicker avoids oil-canning in large panels.
- Roll-formed profiles: 0.024 to 0.040 in in 3105 H14.
- Stamped parts: 0.040 to 0.118 in depending on draw depth.
- Cookware circles: 0.06 to 0.157 in depending on diameter and induction base.
- Ducts and housings: 0.024 to 0.040 in.
If the part already exists, measure thickness with a micrometer at several points and send the average with its range: it is the best specification possible.
Frequently asked questions
How thick is 22 gauge aluminum?
On the Brown & Sharpe chart, 0.0253 in, that is 0.64 mm. Other charts give slightly different values; that is why it is better to order in decimal inches or millimeters.
What gauge aluminum is used for facades?
Between 24 and 16 gauge, that is 0.020 to 0.050 in, depending on panel size and fastening system. Large panels need more thickness to avoid oil-canning.
What is the thinnest sheet Almexa makes?
0.008 in in coil and sheet; 0.0039 in in fin stock; and from 0.00035 in in converted foil.
Leads Almexa Aluminio, Mexico's integrated flat-rolled aluminum mill. Writes about alloys, process, pricing and supply for industrial buyers in North America. LinkedIn