Which Is Thicker, 18 Or 22 Gauge Sheet Metal?

“Which is thicker, 18-gauge or 22-gauge sheet metal?”

Your instinct would be to say 22-gauge, having a higher number, has to be thicker? That’s an illusion! Within the world of sheet metal (whether steel, galvanized sheet, or aluminum), standard gauge numbering systems (as per standards such as American Wire Gauge (AWG) or Birmingham Wire Gauge (BWG)) have one guideline: the higher the number, the thinner the actual thickness of the sheet.

So the moral is: 18-gauge sheet metal, for example, is considerably thicker than 22-gauge sheet metal. This seemingly innocent number difference directly affects a material’s strength, load-carrying capacity, cost, and application. The incorrect use of a gauge can lead to material waste and excessive cost at best, or even structural weakness or product failure at worst.

One must understand the “higher the number, the thinner the sheet” principle. This post will compare 18-gauge and 22-gauge sheet metal actual thickness measurements (millimeters/inches), describe their usage application differences, and demonstrate why accurately calculating gauge thickness is an important initial step to preventing errors in purchasing, designing, or fabricating.

18-Gauge vs. 22-Gauge Metal Sheet Thickness Comparison Quick Reference

Notes:

1. Standard Basis: The values for thickness in the table are based on the most prevalent United States Standard (USS) for steel. It is among the most typical reference standards in industry.
2. Material Variations: The actual thickness of different metals (e.g., stainless steel and aluminum) with the same gauge numbers may vary slightly, but the relative principle of “lower gauge number, thicker” always applies. For example, 18-gauge stainless steel or aluminum plate will still be much thicker than 22-gauge plate of the same metal.
3. Actual Thickness: Always specify the actual material gauge sheet provided by the supplier when ordering, as there are small differences between standards (e.g., the British SWG) or between manufacturers.
4. Conversion Relationships: Remember the useful principle: the larger the gauge number, the thinner the plate.
   

Why Trust This Guide? Leveraging The Practical Experience Of LS Experts

These thickness comparisons and these material selection suggestions don’t originate in cold books or web research. They are a direct consequence of decades of hands-on experience with metal materials by our LS engineering experts.

• Working at Sheet Metal Daily: My colleagues and I cut, test, and manufacture sheet metal in sizes from large storage tanks and pressure vessels to small precision machine parts. We compute, select, weld, and test them in-house. At what pressure does which thickness distort? For what process is which gauge optimum? What combination gives the best cost vs. life trade-off? These things are committed to memory.
• Handled Hundreds of “Improper Thickness Selection” Cases: We’ve had hundreds of jobs end up in rework, delay, and even loss due to incorrect initial material selection (i.e., specifying 22-gauge steel when we needed 18-gauge steel, resulting in insufficient strength, or the opposite, resulting in waste and excess weight). These experiences have intensely taught us the real-world impact of gauge differences.
• Derived from Real Customer Needs: The suggestions in this guide have been derived from the real-world experience of thousands of customers whom we’ve served. We know the underlying requirements and common pain points for sheet metal thickness for most industries (construction, machinery, chemicals, and energy).
• LS Internal Knowledge and Verification: Our results are based on LS’s rigorous internal technical specifications, extensive materials database, and frequent technical audits and experience sharing within our team of engineers. This ensures accurate and relevant information.

Whether you need 18-gauge or 22-gauge steel depends on your specific strength, weight, and budget requirements. Take this guide at its word—it’s derived from international standards and revised and reviewed regularly by LS engineers through actual construction projects to provide the most precise and helpful professional advice. LS is available for additional detailed material selection consulting.

What Do Sheet Metal Gauge Numbers Tell You?

The sheet metal common numbering system (for steel and galvanized steel, specifically) (e.g., 18 Ga., 22 Ga.) is derived primarily from the application of the Birmingham Wire Gauge (BWG) or the practically identical American Wire Gauge (AWG) to sheet metal. It is a very old, standard numbering system.

Fewer numbers mean thicker sheet metal: This is the key to remember! The logic behind this numbering system is in reverse. Different from sizes of apparel, where a higher number means larger size, a higher number means thinner material. Imagine a wire stretched out to be longer (a big number) and basically become thinner (thinner). This applies to sheet metal as well.

Numbers Represent Exact Thickness: Each number represents precisely a given thickness (usually in inches or millimeters). For example:

• 18 Ga. (18 gauge): The standard thickness is approximately 0.0478 inches or 1.214 mm.
• 22 Ga. (22 gauge): The standard thickness is approximately 0.0299 inches or 0.759 mm.

Why are the numbers not continuous? Historically, the wire gauge system developed based on the manufacturing needs of wires of various diameters. Over time, all the in-between numbers have been eliminated except in the sheet metal industry where frequently used numbers (18, 20, 22, 24, and 26) have been kept as standard thickness gauges.

Industry Standard: BWG/AWG is the most common application of sheet metal thickness specification (BS, CS, and SS sheet, specifically) in North America and in most of the world’s markets. It’s utilized extensively in construction, manufacturing, and appliance sectors.

Sheet metal gauge (gage) is a common system of numbers following the Birmingham Wire Gauge (BWG) or the American Wire Gauge (AWG). Its principle is the larger the number, the thinner the sheet. Thus, 18-gauge sheet metal (about 1.214 mm) is thicker than 22-gauge sheet metal (about 0.759 mm). Getting a handle on this counterintuitive principle—the larger the number, the thinner it is—is the key to grasping sheet metal gauge numbers. Practically, the best method of being precise in engineering is to refer to the standard and, if needed, take real measurements.

18-gauge vs. 22-gauge Metal Sheet: How Big Is The Measured Thickness Difference?

Primary Conclusion: 18-gauge metal sheet is considerably thicker than 22-gauge metal sheet. The measured thickness difference is approximately 0.50 mm (or 0.020 inches).

1. Definition of “Gauge”:

Normally, metal sheet gauges are Birmingham Wire Gauge (BWG) and American Standard Wire Gauge (AWG) (steel sheet is normally designated by BWG/SWG). The basic rule is: the larger the gauge, the thinner the thickness. 18-gauge is smaller than 22-gauge, so 18-gauge is thicker.

2. Thickness Measurement Values (Based on Common Standards):

• 18-gauge steel sheet: Typical thickness is normally between 1.20-1.25 mm (approximately 0.0478-0.0492 inches). Our standard measured value is 1.22 mm.
• 22-gauge steel plate: Typical thicknesses are normally between 0.70 to 0.75 mm (approximately 0.0276 to 0.0295 inches). Our standard measured value is 0.72 mm.

3. Measured Thickness Difference:

• Absolute Difference: 1.22 mm (18-gauge) – 0.72 mm (22-gauge) = 0.50 mm.
• Relative Difference: 18-gauge plate is roughly 69.4% thicker than 22-gauge plate (0.50 mm / 0.72 mm = 0.694).

4. Practical Significance:

• Strength and Rigidity: 0.50 mm is significant in sheet metal. 18-gauge plate is more resistant to bending, compressive strength, and rigidity in general than 22-gauge plate.
• Applications: 18-gauge plate would be the standard for structural parts, load-carrying components, chassis, heavy-duty enclosures, and other applications with increased strength demands. 22-gauge sheet metal is more suited to applications where weight is a concern or low-strength demands are required, i.e., light structures, internal brackets, non-load-bearing panels, and exterior shells.
• Cost and Weight: Increased thickness in 18-gauge sheet metal means increased material cost and increased weight of the finished product. The choice should be balanced based on design strength requirements, weight restriction, and cost factor.
• Manufacturing Process: Variation in thickness affects the processing techniques such as bending radius, formability in stamping, and welding parameters.

Machined data clearly shows that 18-gauge sheet metal (approximately 1.22mm) is approximately 0.50mm thicker than 22-gauge sheet metal (approximately 0.72mm). It is not a tiny discrepancy; it is a rather critical parameter that causes enormous differences in mechanical properties, fields of application, and cost. While designing and selecting the materials for LS products, engineers are required to precisely choose the right sheet thickness matching specific functional requirements and performance specifications.

Why Must Medical Device Housings Be Fabricated From 18-gauge Steel?

Medical equipment places extremely stringent requirements on chassis enclosures far beyond what is needed for typical equipment. The necessity for heavier 18-gauge laminate is largely a result of the following basic engineering and safety concerns:

1. Exceptional Structural Strength and Rigidity

Medical equipment (larger or wheeled units such as monitors, ultrasound machines, and workstation carts) goes through a lot of mechanical stress and shock when moved, operated (pushing, pulling, and bumping), cleaned, and serviced.

Heavier 18-gauge laminate is more resistant to bending, denting, and deformation, which enables the enclosure to effectively protect the delicate electronic and mechanical components within, from device failure or component mismatch due to deformation. 22-gauge laminate is not as resistant to deformation under the same conditions.

2. Excellent Electromagnetic Shielding Effectiveness:

Medical environments are filled with other causes of electromagnetic interference (EMI), including other equipment, cellular phones, and Wi-Fi. Even the devices can generate electromagnetic radiation.

The metal casing is the main shield against electromagnetic interference (EMI) and radio frequency interference (RFI). 18-gauge, heavier laminate provides much more shielding than 22-gauge laminate. This is necessary to avoid disturbing sensitive circuits within the device (such as electrocardiograms, electroencephalograms, and low-level biosignal amplifiers) and to prevent disturbance of other devices by the radiation of the device itself (meeting strict EMC standards such as IEC 60601-1-2). Inadequate shielding can lead to incorrect measurements and even make diagnosis or treatment impossible.

3. Increased Protection and Longer Lifetime

Medical equipment enclosures must be capable of withstanding routine and active chemical disinfection (alcohol, chlorine disinfectants, peroxides, etc.) and physical cleaning. 22-gauge thinner steel is more susceptible to wear and perforation due to corrosion or repetitive stress.

18-gauge steel provides more material reserve, significantly increasing the corrosion resistance, wear resistance, and overall service life of the enclosure. This allows the enclosure to remain in integrity and sealing in harsh environments, preventing contaminants or liquids from penetrating the device.

4. High-Reliability Safety Grounding and Protection:

Medical devices are patient safety with extremely high electrical safety demands (IEC 60601-1). The enclosure is a critical component of the protective grounding of the device.

Thicker 18-gauge plate makes a more secure and stronger mechanical point of attachment when connecting to the ground wire, offering a low-impedance and stable ground path in case of a fault, which is critical to prevent hazards of electric shock. Thinner plate will experience issues with connections at the ground screw caused by stress or corrosion.

5. Professional Appearance and User Confidence

More substantial 18-gauge plate generally offers a more substantial, high-tech, and high-quality look and feel, which suits the professional presence of medical devices and makes medical staff and patients even more confident in their quality.

Although 22-gauge plate is thinner, lighter, and less expensive, its structural integrity, electromagnetic shield performance, long-time life, and protection against safety hazards cannot satisfy the high dependability, safety, and regulatory compliance requirements of medical devices. With its large thickness difference, 18-gauge plate provides a key mechanical barrier, electromagnetic interference shielding, and long-term safety assurance for medical device enclosures. It is an essential engineering choice to ensure the stable and safe operation of medical devices in mission-critical applications. In medicine, ruggedness and protection of the device enclosure surpass by far the demand for an ultra-thin design.

How Does PCB No. 22 Reduce Material Cost For Consumer Electronics By 30%?

Reducing material costs by far (targeting 30%) using 22-gauge (lighter) sheet metal rather than heavier sheet metal (e.g., 18-gauge) requires multi-angle collaborative optimization, not just material substitution. The following are key strategies and concepts:

1. Direct Raw Material Savings:

• Weight Reduction per Unit Area: Immediate effect. 22-gauge sheet metal is about 42% thinner than 18-gauge sheet metal. That means for the same area, used metal material weight is about 42% less. For consumer electronics products (such as smartphones, tablets, laptops, headphones, and smart speakers) involving a lot of metal in casings, brackets, shields, or battery covers, material cost is a major component of the bill of materials (BOM).
• Lower Cost of Purchase of Raw Material: Reduced material requirements directly reduce the cost of purchase of metal coils or sheets.

2. Cost Savings from the Optimization of the Manufacturing Process:

• Increased Stamping Speeds: Lighter sheet metal requires less punch force. This allows the stamping press to run at higher speeds, making more parts per unit of time, spreading fixed costs (equipment depreciation, plant space, and overhead) and thus reducing the cost per part.
• Less Die Wear: Forming thin sheet metal applies less wear and stress to dies, extending the life of expensive dies and reducing the frequency and expense of die maintenance and replacement.
• Higher Yield: Thin sheet metal, when properly designed, may be less prone to cracking or excessive springback than thicker sheet metal in certain complicated forming operations, reducing scrap rates and rework costs.
• Reduced Energy Consumption: Energy consumed in forming, stamping, and other processes is reduced.

3. Reduced Warehousing and Logistics Costs:

• Reduced Product Weight: Reducing the net weight of the finished product (especially for products that involve a large number of metal parts) can significantly reduce shipping expenses (air, sea, and ground freight are charged per weight/volume).
• Optimized Storing and Packaging: Slender parts provide more compact packaging, improving the space utilization in warehousing and shipping, and reducing logistic and warehousing costs per unit of product. Even the raw material coils/sheets used are lighter to store and manage.

4. Optimization of Design (Most Important!):

Reducing thickness alone without thinking in terms of design could result in poor structural stiffness or strength. The 30% cost reduction is based on smart design leveraging the properties of thin sheet metal:

• Structural topology optimization: CAE analysis allows for optimal material placement as needed, removing redundant elements, and meeting strength and stiffness demands with minimal material use.
• Adding ribs, flanges, and concave-convex contours: Precisely detailing ribs, flanges, and concave-convex profiles into 22-gauge sheet metal can significantly increase the moment of inertia of the section, significantly improving stiffness and strength, making up for lost performance with thinning, while maintaining total material usage well below the equivalent thicker sheet metal.
• Material consolidation: The easier formability of thin sheet metal allows product formerly constructed of a number of stamped, welded, or riveted parts to be produced with fewer, or even a single, piece, reducing process steps and joining costs.
• Integration with other elements: Using less costly non-metallic materials (engineering plastics and composites) in non-critical structural elements or where special properties are needed (insulation or appearance) with 22-gauge metallic components.

5. Supply Chain and Economies of Scale:

• Mass procurement and better raw material price discounts can be achieved through large-scale applications of No. 22 steel sheets.
• Manufacturing becomes more economical with higher capacity usage.
• Reduced scrap generation and disposal costs.

Baked-in 22-gauge thinning is directly converted into raw material savings and potential efficiencies in processing, and that’s what cost savings are founded on. However, the attainment of a material cost savings of up to 30% requires the combination of highly advanced engineering design (topology optimization and structural reinforcement design) and optimized processes of manufacturing to fully utilize thin sheet without compromising product performance and quality. This is a well-coordinated effort requiring close coordination among engineering, design, manufacturing, and procurement. We have successfully adopted thinner sheet metal for various consumer electronics projects at LS, where huge material cost savings have been achieved in an integrated fashion.