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Standard Sheet Metal Gauges Chart

Last updated:
March 26, 2024
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Understanding Sheet Metal Gauges

Sheet metal gauge charts are indispensable tools, providing a numerical representation of metal thickness. These charts simplify material selection by standardizing measurements.

Gauge and Thickness Relationship

The sheet metal gauge system follows a counterintuitive sequence where a higher gauge number indicates a thinner piece of metal. For instance, a 30-gauge piece is thinner than a 20-gauge piece.

Standard Gauge Systems

Gauge sizes are not universal across all materials. The United States uses the Brown & Sharpe gauge system, which differs from other country-specific systems. Standard gauge charts commonly display measurements in both inches and millimeters.

Gauge Variation in Different Materials

Different materials adhere to different gauge charts. Stainless steel utilizes its own gauge chart, whereas aluminum’s thickness is measured using an aluminum-specific gauge chart. This distinction is crucial for precision in selecting the right gauge for a project.

Commonly Used Sheet Metal Gauges

The gauge system is a standard unit of measure when working with sheet metal, allowing industry professionals to reference material thicknesses efficaciously. It’s imperative to understand that as the gauge number increases, the material thickness decreases for most metals.

Steel Gauge Chart

The sheet metal gauge refers to the thickness of sheet metals. The large the gauge number, the thinner the metal sheet. Please note that for different types of metals, the thickness is different under the same gauge number.

For steel, gauge numbers commonly fall between 3 and 30. The standard gauges for steel usually reflect the material’s weight rather than a direct thickness measurement. Here is a simplified chart for common steel gauges and their corresponding thicknesses in inches and millimeters:

GaugeUS Standard GaugeSheet SteelGalvanized SteelStainless SteelAluminum
6/000.46911.908    0.46911.9050.5814.732
5/000.43811.113    0.43811.1130.51713.119
4/000.40610.32    0.40610.3170.4611.684
3/000.3759.525    0.3759.5250.4110.404
2/000.3448.733    0.3448.730.3659.266
1/000.3137.938    0.3137.9380.3258.252
10.2817.145    0.2817.1420.2897.348
20.2666.746    0.2666.7460.2586.543
30.256.350.2396.073  0.256.350.2295.827
40.2345.9540.2245.695  0.2345.9540.2045.189
50.2195.5580.2095.314  0.2195.5550.1824.62
60.2035.1590.1944.935  0.2035.1590.1624.115
70.1884.7630.1794.554  0.1884.7630.1443.665
310.0110.2770.0110.267  0.0110.2770.0090.226
320.010.2590.010.246  0.010.2590.0080.203
330.0090.2390.0090.229  0.0090.2390.0070.18
340.0090.2180.0080.208  0.0090.2180.0060.16
350.0080.1980.0080.191  0.0080.1980.0060.142
360.0070.1780.0070.17  0.0070.1780.0050.127
370.0070.1680.0060.163  0.0070.1680.0050.114
380.0060.160.0060.152  0.0060.1570.0040.102

Industrial Applications of Sheet Metal Gauges

Sheet metal gauge charts play a crucial role in a variety of industrial applications by providing a standardized reference for material thickness. They guide fabrication processes by specifying the appropriate thickness for different applications, ensuring safety, functionality, and material efficiency.

Automotive Industry Uses

In the automotive industry, sheet metal gauges ensure precise manufacturing of vehicle components. Body panels, for example, need to be thick enough to ensure structural integrity yet thin enough to manage weight:

  • Doors and hoods: Typically utilize 20-gauge steel.
  • Car frames: Often constructed from 12- to 14-gauge steel, depending on the required strength.

Aerospace Industry Uses

For the aerospace industry, the importance of material weight and strength is magnified. Sheet metal gauges help determine the ideal thickness for:

  • Fuselage: Usually made with aluminum sheets between 18-gauge to 22-gauge.
  • Wings: Require a balance of lightness and strength, often utilizing 16-gauge to 20-gauge sheets.

Construction Industry Uses

Sheet metal gauge charts aid the construction industry by specifying material selection for durability and sustainability:

  • Roofing: Typically ranges from 22-gauge to 29-gauge, with thicker gauges for areas with heavy snowfall.
  • HVAC ducts: Commonly use 30-gauge to 24-gauge sheets, where thicker gauges contribute to better insulation and durability.

Tools for Measuring Sheet Metal Gauges

Precision in measuring sheet metal thickness is crucial in many manufacturing and engineering applications. Accurate measurement ensures that the metal meets the required specifications for a given project. Tools such as calipers, micrometers, and gauge wheels are commonly utilized for this purpose.


Calipers are versatile measuring instruments with two opposable arms that can measure the distance between them. They come in various types, including digital, vernier, and dial calipers. Digital calipers are particularly popular due to their ease of use and digital readout that displays measurements quickly and accurately. Measurements are typically available in both metric and imperial units.


Micrometers provide highly precise measurements of sheet metal thickness. They function with a calibrated screw mechanism for fine adjustments and an anvil and spindle that touch the metal surface. Micrometers are favored for their precision, usually measuring thickness to within +/- 0.001 inches (0.025 mm). They also often feature digital screens, although analog versions with a graduated scale are still in use.

Gauge Wheels

Gauge wheels, also known as thickness gauges or gauge sliders, are specialized tools designed specifically for measuring sheet metal. They usually consist of a rotating wheel marked with both the gauge number and corresponding thickness measurements. They are convenient for quickly gauging thickness without the need for a direct reading, providing a visual and tactile reference for sheet metal gauges.

Standards and Specifications

In the realm of sheet metal, specific standards set by institutions like ASTM International and the International Organization for Standardization (ISO) guide manufacturers and consumers in determining the thickness and weight of metal sheets.

ASTM Standards

ASTM International has developed standards that are widely adopted in industries dealing with sheet metal. These standards provide detailed specifications for various grades and materials, ensuring consistency across suppliers. For instance, ASTM A653 pertains to the performance of galvanized steel and defines aspects such as coating weight and bend properties. Another example is ASTM B209, which refers to aluminum and aluminum alloy sheets and plates, and specifies the permissible variations in thickness.

ISO Standards

ISO standards serve as an internationally recognized framework for metal gauge and sheet standards. ISO 3575 defines the specifications for continuously hot-dip zinc-coated cold-reduced carbon steel sheet of commercial and drawing qualities. Additionally, ISO 3548 outlines the thickness tolerances for hot-rolled steel plates. These standards aim to ensure that materials meet consumers’ demands for reliability and quality across global markets.

Safety Considerations in Handling Sheet Metal

When handling sheet metal, workers must prioritize safety due to the material’s sharp edges and potential for creating hazardous metal particles. Adherence to safety guidelines can significantly reduce the risk of accidents and injuries.

Protective Gear: It is essential for individuals working with sheet metal to wear the appropriate protective gear. This includes:

  • Gloves: Heavy-duty gloves to prevent cuts and abrasions
  • Safety Glasses: To protect eyes from metal particles and debris
  • Respiratory Protection: Masks may be necessary to avoid inhaling metal dust

Handling Procedures: Proper handling techniques are important to avoid physical harm:

  • Using the right tools for cutting and bending to maintain control over the sheet metal
  • Ensuring all equipment is correctly maintained and free of defects

Workplace Cleanliness: Keeping the workspace clean reduces the chance of scrap metal causing injuries or being inadvertently carried home, which could expose others to metal particles.

Education and Training: Workers should be well-trained in the correct procedures for handling and manipulating sheet metal, including:

  • How to lift and move large sheets safely to prevent musculoskeletal injuries
  • Recognizing the hazards specific to sheet metal work

By following these safety considerations, workers can minimize the risks associated with handling sheet metal while maintaining productivity and efficiency.

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