The aluminum sheet metal gauge is a numbering system used to describe the thickness of aluminum sheet. Confusingly, a higher gauge number means a thinner sheet. For example, 10 gauge aluminum is thicker than 18 gauge aluminum.
Gauge numbers do not directly correspond to millimetres — they come from an older wire-drawing standard. Always use an aluminum sheet metal gauge thickness chart to convert between gauge, inches, and mm before ordering or fabricating.
| Key Point | Detail |
|---|---|
| Higher gauge number | Thinner sheet — e.g. 22 ga (0.81 mm) is thinner than 10 ga (3.40 mm) |
| Gauge ≠ metric | Gauge numbers do not directly equal mm — always check the chart |
| US standard | Aluminum uses the Brown & Sharpe (B&S) gauge standard in the USA |
| Tolerance band | Each gauge has a permitted thickness tolerance — typically ±0.005″ to ±0.015″ |
Aluminum Sheet Metal Gauge Chart — mm & Inches
This is the full aluminum sheet metal gauge thickness chart covering the most common gauges. All values are for standard aluminum sheet — not steel. Highlighted rows are the most frequently ordered gauges.
| Gauge | Thickness (inches) | Thickness (mm) | Tolerance (±inches) | Common Use |
|---|---|---|---|---|
| 3 ga | 0.2294″ | 5.83 mm | ±0.014″ | Heavy structural plate |
| 4 ga | 0.2043″ | 5.19 mm | ±0.014″ | Heavy duty structural |
| 6 ga | 0.1620″ | 4.11 mm | ±0.012″ | Load-bearing panels |
| 7 ga | 0.1443″ | 3.67 mm | ±0.011″ | Industrial frames |
| 8 ga | 0.1285″ | 3.26 mm | ±0.010″ | Structural panels, brackets |
| 10 ga Popular | 0.1019″ | 2.59 mm | ±0.009″ | Ramps, machine guards, enclosures |
| 11 ga | 0.0907″ | 2.30 mm | ±0.009″ | Truck bodies, brackets |
| 12 ga Popular | 0.0808″ | 2.05 mm | ±0.008″ | Roofing, boat parts, signs |
| 13 ga | 0.0720″ | 1.83 mm | ±0.007″ | General fabrication |
| 14 ga | 0.0641″ | 1.63 mm | ±0.007″ | HVAC, light structural |
| 16 ga | 0.0508″ | 1.29 mm | ±0.006″ | Sheet metal work, ductwork |
| 18 ga Popular | 0.0403″ | 1.02 mm | ±0.005″ | Auto panels, appliances, cabinets |
| 20 ga | 0.0320″ | 0.81 mm | ±0.005″ | Lightweight panels, covers |
| 22 ga | 0.0253″ | 0.64 mm | ±0.004″ | Flashing, decorative trim |
| 24 ga | 0.0201″ | 0.51 mm | ±0.004″ | Light cladding, inserts |
| 26 ga | 0.0159″ | 0.40 mm | ±0.003″ | Foil-weight light sheet |
| 28 ga | 0.0126″ | 0.32 mm | ±0.003″ | Thin wraps, packaging |
Note: These values follow the Brown & Sharpe (B&S) gauge standard for aluminum. Steel gauge charts use different values — never apply a steel gauge chart to aluminum sheet.
Most Common Gauges — Quick Reference
The three most ordered aluminum sheet metal gauge sizes are 10, 12, and 18 gauge. Here is a fast-reference breakdown of each.
10 ga
10 Gauge Aluminum Thickness
Inches0.1019″
Millimetres2.59 mm
Tolerance±0.009″
Weight (kg/m²)~7.0
Best forRamps, guards, frames
12 ga
12 Gauge Aluminum Sheet
Inches0.0808″
Millimetres2.05 mm
Tolerance±0.008″
Weight (kg/m²)~5.5
Best forRoofing, marine, signs
18 ga
18 Gauge Aluminum Thickness
Inches0.0403″
Millimetres1.02 mm
Tolerance±0.005″
Weight (kg/m²)~2.75
Best forAuto panels, cabinets
16 ga
16 Gauge Aluminum Sheet
Inches0.0508″
Millimetres1.29 mm
Tolerance±0.006″
Weight (kg/m²)~3.5
Best forHVAC, ductwork, covers
6061 & 5052 Aluminum Sheet Metal Gauge
While gauge numbers and thicknesses are the same across alloys, the 6061 aluminum sheet metal gauge and aluminum 5052 sheet metal gauge charts differ in available tempers, mechanical properties, and thickness tolerances at each gauge.
6061 Aluminum — Gauge & Properties
| Gauge | Thickness (mm) | Thickness (in) | Temper | Tensile Strength | Best Use |
|---|---|---|---|---|---|
| 8 ga | 3.26 mm | 0.1285″ | T6 | 310 MPa | Structural frames, brackets |
| 10 ga | 2.59 mm | 0.1019″ | T6 | 310 MPa | Aerospace parts, machine frames |
| 12 ga | 2.05 mm | 0.0808″ | T6 | 310 MPa | Transport, structural panels |
| 14 ga | 1.63 mm | 0.0641″ | T4 / T6 | 241 – 310 MPa | General fabrication |
| 16 ga | 1.29 mm | 0.0508″ | T4 | 241 MPa | Sheet metal work, covers |
| 18 ga | 1.02 mm | 0.0403″ | T4 | 241 MPa | Lightweight panels |
5052 Aluminum — Gauge & Properties
| Gauge | Thickness (mm) | Thickness (in) | Temper | Tensile Strength | Best Use |
|---|---|---|---|---|---|
| 8 ga | 3.26 mm | 0.1285″ | H32 | 228 MPa | Marine hulls, fuel tanks |
| 10 ga | 2.59 mm | 0.1019″ | H32 | 228 MPa | Boat parts, pressure vessels |
| 12 ga | 2.05 mm | 0.0808″ | H32 | 228 MPa | Marine, chemical equipment |
| 14 ga | 1.63 mm | 0.0641″ | H32 | 228 MPa | HVAC, ductwork |
| 16 ga | 1.29 mm | 0.0508″ | H32 / H34 | 228 – 262 MPa | General sheet work |
| 18 ga | 1.02 mm | 0.0403″ | H32 | 228 MPa | Automotive, appliances |
| 20 ga | 0.81 mm | 0.0320″ | H32 | 228 MPa | Light cladding, trim |
💡 6061 vs 5052 by gauge: At the same gauge, 6061-T6 is stronger (310 MPa) but 5052-H32 has far better corrosion resistance — especially in saltwater environments. Choose 5052 for marine and chemical use; choose 6061 where strength and machinability matter more.
Aluminum Sheet Metal Gauge Thickness Tolerances
Aluminum sheet metal gauge tolerances define the permitted variation above and below the nominal thickness. These tolerances follow ASTM B209 for aluminum sheet and plate.
| Gauge | Nominal (mm) | Tolerance (±mm) | Tolerance (±inches) | Min (mm) | Max (mm) |
|---|---|---|---|---|---|
| 8 ga | 3.26 | ±0.25 | ±0.010″ | 3.01 | 3.51 |
| 10 ga | 2.59 | ±0.23 | ±0.009″ | 2.36 | 2.82 |
| 12 ga | 2.05 | ±0.20 | ±0.008″ | 1.85 | 2.25 |
| 14 ga | 1.63 | ±0.18 | ±0.007″ | 1.45 | 1.81 |
| 16 ga | 1.29 | ±0.15 | ±0.006″ | 1.14 | 1.44 |
| 18 ga | 1.02 | ±0.13 | ±0.005″ | 0.89 | 1.15 |
| 20 ga | 0.81 | ±0.13 | ±0.005″ | 0.68 | 0.94 |
| 22 ga | 0.64 | ±0.10 | ±0.004″ | 0.54 | 0.74 |
Important: Tolerance bands widen for wider sheets. The values above apply to sheets up to 1220 mm (48″) wide. For sheets over 1500 mm wide, confirm tolerances directly with your supplier or refer to ASTM B209 Table 7.2.
Aluminum Sheet Gauge by Application
Choosing the right aluminum sheet metal gauge for your project depends on the required strength, weight, and formability. Here is a quick guide by end use.
| Application | Recommended Gauge | Thickness (mm) | Alloy |
|---|---|---|---|
| Aerospace structural panels | 8 – 10 ga | 2.59 – 3.26 mm | 6061-T6 |
| Truck body & trailer panels | 10 – 12 ga | 2.05 – 2.59 mm | 5052-H32 |
| Roofing & wall cladding | 12 – 16 ga | 1.29 – 2.05 mm | 3003, 5052 |
| Marine hull & boat parts | 10 – 14 ga | 1.63 – 2.59 mm | 5052-H32 |
| Automotive body panels | 18 – 20 ga | 0.81 – 1.02 mm | 5052, 6061 |
| HVAC ductwork | 16 – 22 ga | 0.64 – 1.29 mm | 3003-H14 |
| Cabinet & enclosure panels | 18 – 20 ga | 0.81 – 1.02 mm | 5052, 3003 |
| Sign blanks & display panels | 22 – 24 ga | 0.51 – 0.64 mm | 1100, 3003 |
| Decorative trim & flashing | 24 – 28 ga | 0.32 – 0.51 mm | 1100, 3003 |
Industries That Use Aluminum Sheet by Gauge
- Aerospace & aviation (8–12 ga)
- Automotive manufacturing (18–22 ga)
- Marine & boatbuilding (10–14 ga)
- Construction & architecture (14–20 ga)
- HVAC & ventilation (18–24 ga)
- Food processing equipment (14–18 ga)
- Electronics enclosures (20–24 ga)
- Transport & trailer bodies (10–14 ga)
Frequently Asked Questions
What is the aluminum sheet metal gauge to mm conversion?
Gauge numbers do not convert to mm by a simple formula — you must use a chart. The most common conversions are: 10 ga = 2.59 mm, 12 ga = 2.05 mm, 16 ga = 1.29 mm, 18 ga = 1.02 mm, 20 ga = 0.81 mm. Note that aluminum uses the Brown & Sharpe gauge standard — different from the steel gauge standard.
What is 12 gauge aluminum thickness in inches and mm?
A 12 gauge aluminum sheet is 0.0808 inches (approximately 2.05 mm) thick. It is one of the most popular gauges for roofing, marine applications, and sign fabrication — offering a good balance of strength and weight.
What is 10 gauge aluminum thickness?
10 gauge aluminum is 0.1019 inches thick, which equals approximately 2.59 mm. It is a heavy-duty gauge used for ramps, machine guards, structural frames, and industrial enclosures where impact resistance is needed.
What is 18 gauge aluminum thickness?
18 gauge aluminum is 0.0403 inches thick, equal to approximately 1.02 mm. It is widely used in automotive body panels, kitchen equipment, appliance housings, and cabinet panels — lightweight yet rigid enough for formed sheet metal parts.
Is aluminum gauge the same as steel gauge?
No. Aluminum and steel use different gauge standards. A 12 gauge steel sheet is approximately 2.66 mm thick, while a 12 gauge aluminum sheet is 2.05 mm. Always use an aluminum-specific gauge chart when working with aluminum sheet metal.
What aluminum sheet metal gauge tolerances should I expect?
Tolerances follow ASTM B209 and vary by gauge and sheet width. For common gauges, typical tolerances are ±0.005″ to ±0.010″ (±0.13 mm to ±0.25 mm). Tolerances increase for wider sheets. Always confirm with your supplier for precision applications.
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