Specifying sheet metal thicknesses without exact decimal conversions leads directly to tolerance stack-up failures and delayed assembly lines. Analyzing thousands of rapid prototyping and production runs reveals that unit confusion between design engineers and fabrication floors is a primary cause of wasted material. For engineering and procurement teams balancing structural integrity with strict cost controls, standardizing around the correct decimal equivalents prevents costly redesigns. The reference tables below provide the exact gauge-to-millimeter and inch conversions required for accurate manufacturing.
Steel Sheet Metal Gauge Calculator
This interactive sheet metal gauge chart tool allows you to input a standard gauge number and immediately see the exact thickness in both inches and millimeters. It eliminates guesswork by cross-referencing industry standards across all common manufacturing metals.
The Complete Sheet Metal Gauge Conversion Chart
Before specifying a gauge on a CAD drawing, you must verify the exact thickness based on the specific material you are using. A single gauge number does not equal a universal thickness across different alloys.
If you’re unsure how to select the right sheet metal gauge or want to learn more detailed information to avoid fabrication mistakes, check out our complete guide for clear answers: https://www.rapiddirect.com/blog/sheet-metal-gauge/
The following metal sheet gauge chart provides the baseline conversions for the most common materials used in manufacturing.
| Gauge | Mild Steel (in / mm) | Stainless Steel (in / mm) | Galvanized (in / mm) | Aluminum (in / mm) | Copper (in / mm) | Brass (in / mm) |
| 10 | 0.1345 (3.416) | 0.1406 (3.571) | 0.1382 (3.510) | 0.1019 (2.588) | 0.1340 (3.404) | 0.1019 (2.588) |
| 11 | 0.1196 (3.038) | 0.1250 (3.175) | 0.1233 (3.132) | 0.0907 (2.304) | 0.1200 (3.048) | 0.0907 (2.305) |
| 12 | 0.1046 (2.657) | 0.1094 (2.779) | 0.1084 (2.753) | 0.0808 (2.052) | 0.1090 (2.769) | 0.0808 (2.053) |
| 14 | 0.0747 (1.897) | 0.0781 (1.984) | 0.0785 (1.994) | 0.0641 (1.628) | 0.0830 (2.108) | 0.0641 (1.628) |
| 16 | 0.0598 (1.519) | 0.0625 (1.588) | 0.0635 (1.613) | 0.0508 (1.290) | 0.0650 (1.651) | 0.0508 (1.291) |
| 18 | 0.0478 (1.214) | 0.0500 (1.270) | 0.0516 (1.311) | 0.0403 (1.024) | 0.0490 (1.245) | 0.0403 (1.024) |
| 20 | 0.0359 (0.912) | 0.0375 (0.953) | 0.0396 (1.006) | 0.0320 (0.813) | 0.0350 (0.889) | 0.0320 (0.812) |
| 22 | 0.0299 (0.759) | 0.0312 (0.792) | 0.0336 (0.853) | 0.0253 (0.643) | 0.0280 (0.711) | 0.0253 (0.644) |
| 24 | 0.0239 (0.607) | 0.0250 (0.635) | 0.0276 (0.701) | 0.0201 (0.511) | 0.0220 (0.559) | 0.0201 (0.511) |
| 26 | 0.0179 (0.455) | 0.0187 (0.475) | 0.0217 (0.551) | 0.0159 (0.404) | 0.0180 (0.457) | 0.0159 (0.405) |
(Note: Data derived from standard manufacturing references.)
Material-Specific Thickness Charts
When evaluating a sheet metal thickness gauge chart, precision is critical. Always refer to the specific chart for your selected alloy.
Steel Sheet Metal Gauge Thickness Chart (Mild/Standard Steel)
Mild steel is the baseline for most structural fabrication. Use this steel sheet metal gauge chart for standard carbon steel applications.
| Gauge | Inches (in) | Millimeters (mm) |
| 7 | 0.1793 | 4.554 |
| 8 | 0.1644 | 4.176 |
| 10 | 0.1345 | 3.416 |
| 12 | 0.1046 | 2.657 |
| 14 | 0.0747 | 1.897 |
| 16 | 0.0598 | 1.519 |
| 18 | 0.0478 | 1.214 |
| 20 | 0.0359 | 0.912 |
| 22 | 0.0299 | 0.759 |
| 24 | 0.0239 | 0.607 |
(Data sourced from standard low carbon steel measurements.)
Stainless Steel Sheet Metal Gauge Chart
Stainless steel is denser and has a different standard thickness curve than standard mild steel.
| Gauge | Inches (in) | Millimeters (mm) |
| 8 | 0.1719 | 4.366 |
| 10 | 0.1406 | 3.571 |
| 12 | 0.1094 | 2.779 |
| 14 | 0.0781 | 1.984 |
| 16 | 0.0625 | 1.588 |
| 18 | 0.0500 | 1.270 |
| 20 | 0.0375 | 0.953 |
| 22 | 0.0312 | 0.792 |
| 24 | 0.0250 | 0.635 |
(Data sourced from standard stainless steel measurements.)
Aluminum Sheet Metal Gauge Thickness Chart
Aluminum uses the AWG standard. An 18-gauge aluminum sheet is significantly thinner than an 18-gauge steel sheet.
| Gauge | Inches (in) | Millimeters (mm) |
| 8 | 0.1285 | 3.264 |
| 10 | 0.1019 | 2.588 |
| 12 | 0.0808 | 2.052 |
| 14 | 0.0641 | 1.628 |
| 16 | 0.0508 | 1.290 |
| 18 | 0.0403 | 1.024 |
| 20 | 0.0320 | 0.813 |
| 22 | 0.0253 | 0.643 |
| 24 | 0.0201 | 0.511 |
(Data sourced from standard aluminum measurements.)
Practical Weight Reference for Mild Steel
Knowing the exact weight of sheet metal gauge sizes helps engineers and procurement teams with part design, packaging planning, and shipment budgeting. These accurate mild steel gauge weight values are essential for verifying sheet metal thickness specifications and logistical cost planning.
Standard mild steel gauge weights are listed below for quick reference, allowing you to check unit weight in both lb/ft² and kg/m² without manual calculation.
Mild Steel Weight Conversion Chart
Shipping heavy metal parts via air freight (e.g., DHL/FedEx) impacts unit economics. Use this table to calculate the logistics weight of mild steel components.
| Gauge | Thickness (mm) | Weight (lb/ft²) | Weight (kg/m²) |
| 10 | 3.416 | 5.487 | 26.790 |
| 12 | 2.657 | 4.267 | 20.834 |
| 14 | 1.897 | 3.047 | 14.879 |
| 16 | 1.519 | 2.440 | 11.911 |
| 18 | 1.214 | 1.950 | 9.521 |
| 20 | 0.912 | 1.465 | 7.151 |
| 22 | 0.759 | 1.220 | 5.955 |
| 24 | 0.607 | 0.975 | 4.760 |
(Data sourced from standard mild steel weight metrics.)
Design for Manufacturability (DFM) Rules
Choosing the right thickness directly impacts the manufacturability of your part, especially during bending and stamping operations.
Pro Tip: When choosing a gauge, use smaller gauge numbers (thicker material) for structural load-bearing components. Use larger gauge numbers (thinner material) for cosmetic outer casings to save weight and cost.
If you are unsure whether your chosen thickness can be formed without cracking, upload your CAD file to RapidDirect’s instant quote platform. The system will automatically run a DFM check, verifying standard tolerances (ISO 2768) and confirming if your bends are feasible for the requested material. RapidDirect can process sheet metal fabrication orders in as fast as one day.
Summary
Relying on a standardized gauge chart sheet metal reference is the only way to align engineering intent with manufacturing reality. Always verify the gauge number against the specific material type, as steel, aluminum, and zinc all follow completely different thickness rules.
Ready to transition your sheet metal design into a physical part? Upload your STEP files to RapidDirect’s online quoting engine. You will receive an instant price, a free automated DFM analysis, and access to rapid manufacturing lead times as fast as 1 day.
FAQs
No. A gauge number corresponds to different actual thicknesses depending on the metal. Steel, aluminum, and zinc use different standard systems.
No. For almost all metals, including steel, a larger gauge number means the material is thinner. 16 gauge is thicker than 18 gauge.
Once a metal piece exceeds 6mm in thickness, the industry generally classifies it as metal plate rather than sheet metal.
Zinc uses a reverse system. For zinc plate, a higher gauge number means the material is thicker, which is the exact opposite of steel or aluminum.
No. You must always label the drawing with both the material type and the gauge number (e.g., “14 Gauge Aluminum”). Failing to specify the material will cause errors on the factory floor.
Yes. Gauges specify the raw material thickness. Applying surface finishes like powder coating or thick anodizing will add fractional millimeters to the final part dimensions.
