Sheet Metal Gauge Converter
A sheet metal gauge converter translates gauge numbers into actual thickness measurements in inches and millimeters. Since gauge thickness varies by metal type, select your material and enter a gauge number to see the exact thickness for steel, stainless steel, aluminum, or galvanized steel.
What Is Sheet Metal Gauge?
Sheet metal gauge is a numerical system used to express the thickness of metal sheet. Counterintuitively, higher gauge numbers indicate thinner metal. A 24 gauge sheet is thinner than a 16 gauge sheet. The gauge system developed in the 19th century from the wire drawing industry, where the gauge number originally indicated how many times wire had been drawn through progressively smaller dies.
There is no single universal gauge-to-thickness standard. The gauge system used depends entirely on the type of metal. Steel uses the Manufacturers Standard Gauge (MSG), aluminum uses the Brown and Sharpe (B&S) system, and galvanized steel has its own separate chart. This means that 18 gauge steel and 18 gauge aluminum are two different thicknesses. Always specify the material type when ordering sheet metal by gauge. See the Engineering Toolbox sheet metal gauge reference for a comprehensive breakdown by material.
Why Gauge Varies by Metal Type
The reason gauge thicknesses differ by material comes from the historical development of the gauge system. Each industry, whether wire, steel, or non-ferrous metals, developed its own conventions based on the manufacturing processes of the time. Steel producers settled on the Manufacturers Standard Gauge based on weight per square foot of mild steel. Aluminum producers adopted the Brown and Sharpe AWG system originally designed for wire.
The ASTM sheet metal thickness standards now specify thickness in decimal inches or millimeters for precision manufacturing, with gauge numbers used primarily as a shorthand reference in ordering and fabrication contexts. Many engineering drawings now specify thickness directly in decimal form rather than gauge to avoid ambiguity.
Steel Gauge Chart
Manufacturers Standard Gauge (MSG) for carbon steel and sheet steel.
| Gauge | Inches | Millimeters |
|---|---|---|
| 7 | 0.1793" | 4.554 mm |
| 8 | 0.1644" | 4.176 mm |
| 9 | 0.1495" | 3.797 mm |
| 10 | 0.1345" | 3.416 mm |
| 11 | 0.1196" | 3.038 mm |
| 12 | 0.1046" | 2.657 mm |
| 13 | 0.0897" | 2.278 mm |
| 14 | 0.0747" | 1.897 mm |
| 15 | 0.0673" | 1.709 mm |
| 16 | 0.0598" | 1.519 mm |
| 17 | 0.0538" | 1.367 mm |
| 18 | 0.0478" | 1.214 mm |
| 19 | 0.0418" | 1.062 mm |
| 20 | 0.0359" | 0.912 mm |
| 21 | 0.0329" | 0.836 mm |
| 22 | 0.0299" | 0.759 mm |
| 23 | 0.0269" | 0.683 mm |
| 24 | 0.0239" | 0.607 mm |
| 25 | 0.0209" | 0.531 mm |
| 26 | 0.0179" | 0.455 mm |
| 27 | 0.0164" | 0.417 mm |
| 28 | 0.0149" | 0.378 mm |
| 29 | 0.0135" | 0.343 mm |
| 30 | 0.0120" | 0.305 mm |
Stainless Steel Gauge Chart
Stainless steel uses the same Manufacturers Standard Gauge system but with slightly different nominal thicknesses based on stainless alloy density.
| Gauge | Inches | Millimeters |
|---|---|---|
| 7 | 0.1875" | 4.763 mm |
| 8 | 0.1719" | 4.366 mm |
| 9 | 0.1563" | 3.969 mm |
| 10 | 0.1406" | 3.571 mm |
| 11 | 0.1250" | 3.175 mm |
| 12 | 0.1094" | 2.778 mm |
| 13 | 0.0938" | 2.381 mm |
| 14 | 0.0781" | 1.984 mm |
| 15 | 0.0703" | 1.786 mm |
| 16 | 0.0625" | 1.588 mm |
| 17 | 0.0563" | 1.429 mm |
| 18 | 0.0500" | 1.270 mm |
| 19 | 0.0438" | 1.111 mm |
| 20 | 0.0375" | 0.953 mm |
| 21 | 0.0344" | 0.874 mm |
| 22 | 0.0313" | 0.794 mm |
| 23 | 0.0281" | 0.714 mm |
| 24 | 0.0250" | 0.635 mm |
| 25 | 0.0219" | 0.556 mm |
| 26 | 0.0188" | 0.477 mm |
| 28 | 0.0156" | 0.396 mm |
| 30 | 0.0125" | 0.318 mm |
Aluminum Gauge Chart
Aluminum uses the Brown and Sharpe (B&S) gauge system, also known as the American Wire Gauge (AWG) for non-ferrous metals.
| Gauge | Inches | Millimeters |
|---|---|---|
| 7 | 0.1443" | 3.665 mm |
| 8 | 0.1285" | 3.264 mm |
| 9 | 0.1144" | 2.906 mm |
| 10 | 0.1019" | 2.588 mm |
| 11 | 0.0907" | 2.304 mm |
| 12 | 0.0808" | 2.052 mm |
| 13 | 0.0720" | 1.829 mm |
| 14 | 0.0641" | 1.628 mm |
| 15 | 0.0571" | 1.450 mm |
| 16 | 0.0508" | 1.290 mm |
| 17 | 0.0453" | 1.151 mm |
| 18 | 0.0403" | 1.024 mm |
| 19 | 0.0359" | 0.912 mm |
| 20 | 0.0320" | 0.813 mm |
| 21 | 0.0285" | 0.724 mm |
| 22 | 0.0253" | 0.643 mm |
| 23 | 0.0226" | 0.574 mm |
| 24 | 0.0201" | 0.511 mm |
| 25 | 0.0179" | 0.455 mm |
| 26 | 0.0159" | 0.404 mm |
| 28 | 0.0126" | 0.320 mm |
| 30 | 0.0100" | 0.254 mm |
Galvanized Steel Gauge Chart
Galvanized steel has a separate gauge chart. The zinc coating adds thickness, making galvanized sheet slightly thicker than bare steel at the same gauge number.
| Gauge | Inches | Millimeters |
|---|---|---|
| 8 | 0.1681" | 4.270 mm |
| 9 | 0.1532" | 3.891 mm |
| 10 | 0.1382" | 3.510 mm |
| 11 | 0.1233" | 3.132 mm |
| 12 | 0.1084" | 2.753 mm |
| 13 | 0.0934" | 2.372 mm |
| 14 | 0.0785" | 1.994 mm |
| 15 | 0.0710" | 1.803 mm |
| 16 | 0.0635" | 1.613 mm |
| 17 | 0.0575" | 1.461 mm |
| 18 | 0.0516" | 1.311 mm |
| 19 | 0.0456" | 1.158 mm |
| 20 | 0.0396" | 1.006 mm |
| 21 | 0.0366" | 0.930 mm |
| 22 | 0.0336" | 0.853 mm |
| 23 | 0.0306" | 0.777 mm |
| 24 | 0.0276" | 0.701 mm |
| 25 | 0.0247" | 0.627 mm |
| 26 | 0.0217" | 0.551 mm |
| 27 | 0.0202" | 0.513 mm |
| 28 | 0.0187" | 0.475 mm |
| 29 | 0.0172" | 0.437 mm |
| 30 | 0.0157" | 0.399 mm |
Common Gauge Conversions
24 Gauge in mm
24 gauge steel is 0.0239 inches thick, which equals 0.607 mm. This is one of the most commonly used gauges in HVAC ductwork, light-gauge framing, and automotive body panels. 24 gauge stainless steel is slightly thicker at 0.0250 inches (0.635 mm), and 24 gauge aluminum is 0.0201 inches (0.511 mm). The Thomasnet sheet metal gauge guide covers gauge standards for HVAC and fabrication.
20 Gauge in mm
20 gauge steel is 0.0359 inches thick, equaling 0.912 mm. It is commonly used in electrical enclosures, appliance housings, and light structural applications. 20 gauge stainless steel is 0.0375 inches (0.953 mm) and is frequently used in commercial kitchen equipment and food processing surfaces.
16 Gauge in mm
16 gauge steel is 0.0598 inches thick, equaling 1.519 mm. This is a heavier sheet metal used for structural supports, brackets, heavy-duty enclosures, and commercial HVAC. 16 gauge stainless steel is 0.0625 inches (1.588 mm) and is the standard for commercial sinks, countertops, and industrial food equipment.
How to Measure Sheet Metal Thickness
The most accurate way to measure sheet metal thickness is with a digital micrometer or caliper. A micrometer can measure to 0.0001 inch accuracy, making it precise enough to confirm gauge. Sheet metal gauges typically vary by 0.003 to 0.015 inches between consecutive gauge numbers, so calipers with 0.001 inch resolution are sufficient for most identification purposes.
A sheet metal gauge tool, also called a gauge selector or gauge wheel, is a physical disc with notched slots cut to the standard thickness of each gauge for a specific metal. You insert the metal into the slots until you find the one that fits snugly without forcing. These tools are inexpensive and common in sheet metal shops, but are only calibrated for a specific metal type.
When measuring galvanized steel, be aware that the zinc coating contributes to the total thickness. The base steel thickness and the galvanized gauge chart thickness will differ by approximately the coating thickness. For precision work, always use the tenths to inches converter or micrometer measurements rather than nominal gauge values.
Frequently Asked Questions
What thickness is 24 gauge sheet metal?
24 gauge thickness depends on the material. Steel: 0.0239 inches (0.607 mm). Stainless steel: 0.0250 inches (0.635 mm). Aluminum: 0.0201 inches (0.511 mm). Galvanized steel: 0.0276 inches (0.701 mm). Always confirm the material type before specifying gauge, as the same gauge number means different thicknesses for different metals.
What is 20 gauge in mm for steel?
20 gauge steel is 0.0359 inches thick, which converts to 0.912 mm. This is the Manufacturers Standard Gauge (MSG) value for carbon steel. For stainless steel, 20 gauge is 0.0375 inches (0.953 mm). For aluminum, 20 gauge (B&S) is 0.0320 inches (0.813 mm).
Is a higher gauge number thicker or thinner?
Higher gauge numbers are thinner. This is one of the most common sources of confusion with sheet metal. 10 gauge steel (0.1345 inches) is much thicker and heavier than 24 gauge steel (0.0239 inches). Think of it as the number of times the metal was rolled or drawn: more passes produce thinner material and a higher gauge number.
What gauge is 1mm steel?
1mm steel is closest to 20 gauge (0.912 mm) or 19 gauge (1.062 mm) in the Manufacturers Standard Gauge chart. 20 gauge at 0.912 mm is within 0.09 mm of 1mm, making it the nearest standard gauge. For stainless steel, 18 gauge (1.270 mm) and 20 gauge (0.953 mm) bracket 1mm, with 20 gauge being the closest.
What is the most common sheet metal gauge?
The most common gauges depend on the application. 16 gauge is the most common for structural steel applications, brackets, and heavy enclosures. 18 gauge is standard for moderate structural use and commercial kitchen stainless steel. 20 gauge is common for light steel fabrication and appliance panels. 24 gauge is the standard for HVAC ductwork in most residential and light commercial applications.