Sheet Metal Gauge Chart
Complete thickness conversion guide for sheet metal gauges. Convert gauge numbers to millimeters and inches for carbon steel, stainless steel, aluminum, galvanized steel, and more.
Gauge Thickness Converter
Conversion Results:
Thickness (mm)
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Thickness (inches)
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Weight (kg/m²)
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Common Use
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Standard Carbon Steel Gauge Chart (ASTM / USS)
United States Standard (USS) sheet metal gauge for carbon steel, hot rolled and cold rolled steel sheets and coils.
| Gauge | Thickness (inches) | Thickness (mm) | Weight (lb/ft²) | Weight (kg/m²) | Common Applications |
|---|---|---|---|---|---|
| 3 | 0.2391 | 6.073 | 9.76 | 47.68 | Heavy structural applications |
| 4 | 0.2242 | 5.695 | 9.15 | 44.71 | Industrial equipment, heavy panels |
| 5 | 0.2092 | 5.314 | 8.54 | 41.73 | Structural supports, bases |
| 6 | 0.1943 | 4.935 | 7.93 | 38.76 | Machine bases, heavy duty panels |
| 7 | 0.1793 | 4.554 | 7.32 | 35.78 | Automotive frames, heavy fabrication |
| 8 | 0.1644 | 4.176 | 6.71 | 32.81 | Truck bodies, containers |
| 10 | 0.1345 | 3.416 | 5.49 | 26.85 | Floor plates, equipment covers |
| 11 | 0.1196 | 3.038 | 4.88 | 23.87 | Industrial shelving, brackets |
| 12 | 0.1046 | 2.657 | 4.27 | 20.89 | Automotive panels, appliances |
| 13 | 0.0897 | 2.278 | 3.66 | 17.91 | Light structural, ductwork |
| 14 | 0.0747 | 1.897 | 3.05 | 14.93 | Automotive body panels, general fabrication |
| 15 | 0.0673 | 1.709 | 2.74 | 13.41 | Light panels, cabinet work |
| 16 | 0.0598 | 1.519 | 2.44 | 11.93 | HVAC ductwork, general metalwork |
| 18 | 0.0478 | 1.214 | 1.95 | 9.54 | Light ductwork, decorative panels |
| 20 | 0.0359 | 0.912 | 1.46 | 7.15 | Electrical boxes, light enclosures |
| 22 | 0.0299 | 0.759 | 1.22 | 5.96 | Roofing, siding, flashing |
| 24 | 0.0239 | 0.607 | 0.98 | 4.77 | Ductwork, gutters, downspouts |
| 26 | 0.0179 | 0.455 | 0.73 | 3.58 | Light roofing, decorative trim |
| 28 | 0.0149 | 0.378 | 0.61 | 2.97 | Very light fabrication, trim |
| 30 | 0.0120 | 0.305 | 0.49 | 2.39 | Lightweight trim, shims |
Galvanized Steel Gauge Chart
Gauge thickness for galvanized steel sheets (includes base steel + zinc coating). Weights are approximate and include standard G90 coating.
| Gauge | Thickness (inches) | Thickness (mm) | Weight (lb/ft²) | Weight (kg/m²) | Coating Standard |
|---|---|---|---|---|---|
| 8 | 0.1681 | 4.270 | 7.03 | 34.37 | G90 |
| 10 | 0.1382 | 3.510 | 5.78 | 28.26 | G90 |
| 11 | 0.1233 | 3.132 | 5.16 | 25.22 | G90 |
| 12 | 0.1084 | 2.753 | 4.53 | 22.16 | G90 |
| 14 | 0.0785 | 1.994 | 3.28 | 16.04 | G90 |
| 16 | 0.0635 | 1.613 | 2.66 | 13.00 | G90 |
| 18 | 0.0516 | 1.311 | 2.16 | 10.56 | G90 |
| 20 | 0.0396 | 1.006 | 1.66 | 8.11 | G90 |
| 22 | 0.0336 | 0.853 | 1.41 | 6.88 | G90 |
| 24 | 0.0276 | 0.701 | 1.16 | 5.65 | G90 |
| 26 | 0.0217 | 0.551 | 0.91 | 4.43 | G90 |
| 28 | 0.0187 | 0.475 | 0.78 | 3.82 | G90 |
| 30 | 0.0157 | 0.399 | 0.66 | 3.21 | G90 |
Stainless Steel Gauge Chart (ASTM A480)
Gauge thicknesses for stainless steel sheets (304, 316, 430, etc.). Based on ASTM A480/A480M standard.
| Gauge | Thickness (inches) | Thickness (mm) | Weight 304 (lb/ft²) | Weight 304 (kg/m²) | Common Applications |
|---|---|---|---|---|---|
| 3 | 0.2391 | 6.073 | 10.00 | 48.88 | Heavy industrial equipment |
| 4 | 0.2242 | 5.695 | 9.38 | 45.85 | Food processing tanks |
| 5 | 0.2092 | 5.314 | 8.75 | 42.77 | Pressure vessels, tanks |
| 6 | 0.1943 | 4.935 | 8.13 | 39.74 | Chemical processing equipment |
| 7 | 0.1793 | 4.554 | 7.50 | 36.66 | Industrial kitchens, breweries |
| 8 | 0.1644 | 4.176 | 6.88 | 33.62 | Commercial kitchen equipment |
| 10 | 0.1345 | 3.416 | 5.63 | 27.51 | Food service countertops |
| 11 | 0.1196 | 3.038 | 5.00 | 24.44 | Sinks, backsplashes |
| 12 | 0.1046 | 2.657 | 4.38 | 21.40 | Appliance panels, trim |
| 14 | 0.0747 | 1.897 | 3.13 | 15.29 | Architectural panels, cladding |
| 16 | 0.0598 | 1.519 | 2.50 | 12.23 | Countertops, decorative panels |
| 18 | 0.0478 | 1.214 | 2.00 | 9.78 | Splashbacks, decorative trim |
| 20 | 0.0359 | 0.912 | 1.50 | 7.33 | Light cladding, trim work |
| 22 | 0.0299 | 0.759 | 1.25 | 6.11 | Decorative applications |
| 24 | 0.0239 | 0.607 | 1.00 | 4.89 | Light decorative work |
Aluminum Sheet Gauge Chart
Gauge thicknesses for aluminum sheets (1100, 3003, 5052, 6061 alloys). Weights based on density 2.71 g/cm³.
| Gauge | Thickness (inches) | Thickness (mm) | Weight (lb/ft²) | Weight (kg/m²) | Common Alloys |
|---|---|---|---|---|---|
| 3 | 0.2391 | 6.073 | 3.46 | 16.93 | 5052, 6061 |
| 4 | 0.2242 | 5.695 | 3.24 | 15.86 | 5052, 6061 |
| 5 | 0.2092 | 5.314 | 3.03 | 14.81 | 3003, 5052 |
| 6 | 0.1943 | 4.935 | 2.81 | 13.75 | 3003, 5052 |
| 7 | 0.1793 | 4.554 | 2.59 | 12.69 | 3003, 5052 |
| 8 | 0.1644 | 4.176 | 2.38 | 11.64 | 3003, 5052 |
| 10 | 0.1345 | 3.416 | 1.95 | 9.52 | 1100, 3003 |
| 11 | 0.1196 | 3.038 | 1.73 | 8.47 | 1100, 3003 |
| 12 | 0.1046 | 2.657 | 1.51 | 7.40 | 1100, 3003 |
| 14 | 0.0747 | 1.897 | 1.08 | 5.28 | 1100, 3003 |
| 16 | 0.0598 | 1.519 | 0.86 | 4.23 | 1100, 3003 |
| 18 | 0.0478 | 1.214 | 0.69 | 3.38 | 1100, 3003 |
| 20 | 0.0359 | 0.912 | 0.52 | 2.54 | 1100 |
| 22 | 0.0299 | 0.759 | 0.43 | 2.11 | 1100 |
| 24 | 0.0239 | 0.607 | 0.35 | 1.69 | 1100 |
Metric Thickness Standards (ISO / EN / GB)
Common metric sheet metal thicknesses used in Europe, Asia, and international markets. Not directly equivalent to gauge system.
| Thickness (mm) | Thickness (inches) | Weight (kg/m²) - Steel | Approximate Gauge | Common Applications |
|---|---|---|---|---|
| 0.3 | 0.0118 | 2.36 | ~30 | Light trim, shims |
| 0.4 | 0.0157 | 3.14 | ~28 | Decorative panels |
| 0.5 | 0.0197 | 3.93 | ~26 | Roofing, cladding |
| 0.6 | 0.0236 | 4.71 | ~24 | Ductwork, gutters |
| 0.7 | 0.0276 | 5.50 | ~23 | Light fabrication |
| 0.8 | 0.0315 | 6.28 | ~22 | Automotive panels |
| 1.0 | 0.0394 | 7.85 | ~20 | Electrical enclosures |
| 1.2 | 0.0472 | 9.42 | ~18 | HVAC, light structural |
| 1.5 | 0.0591 | 11.78 | ~16 | General fabrication |
| 2.0 | 0.0787 | 15.70 | ~14 | Automotive, appliances |
| 2.5 | 0.0984 | 19.63 | ~12 | Structural components |
| 3.0 | 0.1181 | 23.55 | ~11 | Industrial equipment |
| 4.0 | 0.1575 | 31.40 | ~8 | Heavy fabrication |
| 5.0 | 0.1969 | 39.25 | ~6 | Structural supports |
| 6.0 | 0.2362 | 47.10 | ~3 | Heavy duty structures |
Understanding Gauge Systems
Different gauge standards exist for various materials and regions. Understanding these differences is critical for accurate specification.
Common Gauge Standards
- USS (United States Standard): Most common in USA for carbon steel sheets, plates, and strips
- ASTM A480: Specific to stainless steel sheets and plates
- AWG (American Wire Gauge): Used for non-ferrous metals like aluminum, copper, brass
- BWG (Birmingham Wire Gauge): Historical standard, still used for some tube/pipe applications
- SWG (Standard Wire Gauge): British standard, used in UK and Commonwealth countries
- Metric Standards: Direct thickness specification in mm (ISO, EN, GB, JIS)
Key Differences
- Material Variation: Same gauge number = different thickness for steel vs. aluminum vs. stainless
- Non-Linear Scale: Gauge numbers don't scale linearly; smaller gauge = thicker material
- Regional Standards: American vs. British vs. Asian standards differ significantly
- Coating Considerations: Galvanized gauges include base metal + coating thickness
Gauge vs. Thickness Formula
For standard carbon steel (USS):
Thickness (inches) ≈ 0.005 × (31 - Gauge Number)
This is an approximation only. Always refer to official gauge charts for precise values.
Important Notice
Never assume gauge equivalence across materials or standards. Always specify both gauge number AND actual thickness (in mm or inches) on drawings and purchase orders to avoid costly errors. When in doubt, use metric thickness specifications for clarity.Thickness Tolerances
Manufacturing tolerances for sheet metal thicknesses per major standards.
ASTM A1008 (Cold Rolled Steel)
- Thickness 0.015" - 0.033": ±0.002"
- Thickness 0.034" - 0.067": ±0.003"
- Thickness 0.068" - 0.125": ±0.005"
- Thickness 0.126" - 0.187": ±0.007"
ASTM A480 (Stainless Steel)
- Thickness ≤ 0.1875": ±0.005"
- Thickness 0.1876" - 0.250": ±0.010"
- Width ≤ 48": tighter tolerance class available
EN 10051 (European Hot Rolled)
- Thickness < 2.0 mm: ±0.15 mm
- Thickness 2.0 - 3.0 mm: ±0.20 mm
- Thickness 3.0 - 5.0 mm: ±0.30 mm
- Thickness > 5.0 mm: ±5% of nominal
How to Use This Chart
- 1Identify your material type — Carbon steel, galvanized, stainless steel, or aluminum each have different gauge-to-thickness conversions
- 2Find the gauge number — Locate your gauge number in the appropriate chart (lower gauge = thicker metal)
- 3Read thickness and weight — Convert to mm or inches, and check weight per square meter for material calculations
- 4Verify for your region — If working internationally, confirm which gauge standard applies (USS, SWG, metric, etc.)
Frequently Asked Questions
Why do different materials have different gauge thicknesses?
The gauge system was developed separately for different materials based on historical manufacturing processes. Steel gauge is based on weight per unit area, while aluminum and stainless steel use different standards. This is why 16 gauge steel (1.5mm) is much thicker than 16 gauge stainless (1.5mm) or aluminum. Always verify the material-specific chart.
Is 16 gauge or 18 gauge thicker?
16 gauge is thicker. In the gauge system, smaller numbers = thicker material. So 16 gauge (~1.5mm) is thicker than 18 gauge (~1.2mm). This counter-intuitive system originated from the number of drawing operations needed to produce wire/sheet—fewer operations (lower gauge) meant thicker material.
What's the most common gauge for automotive panels?
Automotive body panels typically use 20-22 gauge (0.8-1.0mm) cold rolled steel for outer panels, and 18-20 gauge (1.0-1.2mm) for structural reinforcements. Modern vehicles increasingly use high-strength steel at thinner gauges (22-24) to reduce weight while maintaining strength.
How do I convert gauge to metric thickness?
Use the material-specific conversion chart above. For example, 16 gauge carbon steel = 1.519mm, 16 gauge stainless = 1.519mm, but 16 gauge aluminum uses the same gauge number but different actual thickness. There's no universal formula—always use the chart for your specific material type.
What gauge is best for roofing and siding?
Residential roofing typically uses 26-29 gauge galvanized or Galvalume steel (0.4-0.5mm). Commercial roofing uses 22-24 gauge (0.6-0.8mm) for greater durability. Siding ranges from 26-29 gauge for residential to 24-26 gauge for commercial. Thicker gauges provide better dent resistance and longevity but cost more.
Does galvanized coating add to the gauge thickness?
Yes, galvanized gauge measurements include the base steel PLUS the zinc coating thickness. A G90 coating adds approximately 0.002" (0.05mm) total thickness. When comparing galvanized to bare steel, the galvanized sheet will be slightly thicker at the same gauge number.
Can I use American gauge numbers in Europe or Asia?
Not reliably. Europe and Asia primarily use metric thickness specifications (mm) rather than gauge numbers. British SWG (Standard Wire Gauge) differs from American USS gauge. For international projects, always specify thickness in millimeters to avoid confusion and costly errors.
What tolerance should I expect on gauge thickness?
Tolerances vary by thickness and standard. For cold rolled steel under 2mm, expect ±0.05-0.10mm. Hot rolled and galvanized have wider tolerances (±0.15-0.30mm). Precision-ground stock can achieve ±0.02mm but costs significantly more. Always check the applicable ASTM or EN standard for your specific material and thickness.
