A sheet metal gauge chart converts a gauge designation into a nominal thickness for a specific material. For example, 14 gauge carbon steel is 0.0747 in, or approximately 1.897 mm; 14 gauge stainless steel is 0.0781 in, or approximately 1.984 mm. The material and gauge system must be identified before selecting a thickness.
The charts below cover common gauges from 10 to 26 for bare carbon steel, stainless steel, galvanized steel and aluminum. Use them for lookup, then specify the required material, decimal thickness and applicable tolerance on the drawing or purchase order.
Common sheet metal gauge charts by material
For the material tables below, a higher gauge number means a thinner sheet. The steps are not uniform, and a gauge number is neither an inch nor a millimeter measurement.
Choose the material first. A bare “14 gauge” requirement is incomplete.
The inch entries are published nominal reference values. Millimeters are calculated from those displayed entries and rounded to three decimal places. Supplier charts that retain more inch decimals may differ in the last metric digit. These figures do not define manufacturing tolerances or guarantee local stock availability.
Carbon Steel Gauge Chart
This table uses the common Manufacturers’ Standard Gauge (MSG) values for uncoated sheet steel. It should not be confused with the separate U.S. Standard Gauge table discussed in the 1/8-inch section.
| Gauge | Nominal thickness, in / mm |
|---|---|
| 10 | 0.1345 / 3.416 |
| 11 | 0.1196 / 3.038 |
| 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 |
| 26 | 0.0179 / 0.455 |
Stainless Steel Gauge Chart
The nominal 14 gauge stainless steel thickness in this table is 0.0781 in, approximately 1.984 mm. A gauge number identifies a thickness reference, while a grade such as 304 or 316 identifies the material. Both belong in the specification.
| Gauge | Nominal thickness, in / mm |
|---|---|
| 10 | 0.1406 / 3.571 |
| 11 | 0.1250 / 3.175 |
| 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 |
| 26 | 0.0187 / 0.475 |
Galvanized Steel Gauge Chart
Use the galvanized reference rather than the bare-steel column. For ordering and inspection, also clarify whether the required thickness applies to the steel substrate or the coated sheet. The coating designation is a separate requirement.
| Gauge | Nominal thickness, in / mm |
|---|---|
| 10 | 0.1382 / 3.510 |
| 11 | 0.1233 / 3.132 |
| 12 | 0.1084 / 2.753 |
| 14 | 0.0785 / 1.994 |
| 16 | 0.0635 / 1.613 |
| 18 | 0.0516 / 1.311 |
| 20 | 0.0396 / 1.006 |
| 22 | 0.0336 / 0.853 |
| 24 | 0.0276 / 0.701 |
| 26 | 0.0217 / 0.551 |
Aluminum Gauge Chart
Use these aluminum entries for gauge lookup. If the required material is sold by decimal thickness, preserve that dimension in the order rather than substituting the nearest gauge without approval.
| Gauge | Nominal thickness, in / mm |
|---|---|
| 10 | 0.1019 / 2.588 |
| 11 | 0.0907 / 2.304 |
| 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 |
| 26 | 0.0159 / 0.404 |
How to Convert Gauge to Millimeters
To convert metal gauge to mm, first identify the material and look up its nominal inch thickness. Then use:
Thickness in mm = thickness in inches × 25.4
For example, 14 gauge bare carbon steel is 0.0747 × 25.4 = 1.89738 mm, shown as 1.897 mm in the table. The inch-to-millimeter conversion is exact; the gauge entry remains a nominal reference value.
Do not interpolate between gauge numbers as though the scale were linear. If the required thickness falls between listed gauges, specify the thickness and ask the supplier to confirm a suitable product.
Common sheet metal gauge chart lookups
how thick is 12 gauge steel?
For bare carbon steel using MSG, 12 gauge is nominally 0.1046 in, approximately 2.657 mm. The same gauge in the stainless table is 0.1094 in, approximately 2.779 mm. Confirm the material before treating “12 gauge steel” as a complete thickness requirement.
14 gauge to mm: which material?
The 14 gauge metal thickness depends on the selected chart: approximately 1.897 mm for bare carbon steel, 1.984 mm for stainless steel, 1.994 mm for galvanized steel and 1.628 mm for aluminum.
A specified 2.000 mm sheet is therefore a different nominal requirement from 14 gauge carbon steel. Approve any substitution against the drawing and its tolerance, rather than treating a nearby metric size as an automatic equivalent.
16 gauge metal is how thick?
In these tables, 16 gauge is nominally 0.0598 in (1.519 mm) for bare carbon steel, 0.0625 in (1.588 mm) for stainless, 0.0635 in (1.613 mm) for galvanized steel and 0.0508 in (1.290 mm) for aluminum. Material identification is essential to the answer.
Other Common Steel Thickness Lookups
The following short answers use bare carbon steel, MSG. Read the stainless, galvanized or aluminum table when the material differs.
| Thickness lookup | Nominal bare carbon steel thickness |
|---|---|
| 10 gauge steel thickness inches | 0.1345 in, approximately 3.416 mm |
| 11ga steel thickness | 0.1196 in, approximately 3.038 mm |
| 18 gauge steel thickness | 0.0478 in, approximately 1.214 mm |
| 22 ga metal thickness | 0.0299 in, approximately 0.759 mm |
| 24 ga steel thickness | 0.0239 in, approximately 0.607 mm |
what gauge steel is 1/8 inch?
1/8 inch equals 0.1250 in, or 3.175 mm. It corresponds to 11 gauge in the U.S. Standard Gauge table and in the stainless reference above. In the common MSG carbon-steel table, 11 gauge is the closest listed size, at 0.1196 in, but it is not an exact match.
This difference explains why two charts can give apparently conflicting answers:
| Reference system or material | Nominal 11 gauge thickness |
|---|---|
| Manufacturers’ Standard Gauge, bare sheet steel | 0.1196 in |
| U.S. Standard Gauge, sheet and plate iron and steel | 0.1250 in |
| Stainless steel reference used above | 0.1250 in |
The difference between 0.1250 and 0.1196 in is 0.0054 in, or 0.13716 mm. This is a calculation from the two nominal values, not a permitted tolerance or a measured production result.
If the design requires 1/8-inch steel, order the required grade at 0.1250 in nominal thickness and state the applicable tolerance. Confirm the product with the supplier rather than replacing the requirement with “11 gauge” alone.
Have a part drawing with conflicting gauge and thickness notes?
Send the drawing with your sheet metal inquiry and identify which dimension controls. Include the material grade, quantity and any permitted thickness alternatives so the quotation can address the intended requirement.
Galvanized Sheet: Gauge, Coating and Finished Thickness
For galvanized sheet, distinguish three items:
- Steel substrate thickness: the base metal beneath the zinc.
- Coating designation: the specified zinc coating requirement.
- Overall thickness: the substrate plus the coatings on both faces.
G90 is a coating-weight designation. GalvInfo describes it as a minimum triple-spot-test average of 0.90 oz/ft², total both sides. It does not mean 90 gauge, and it does not specify the sheet’s overall thickness.
Do not subtract the bare-steel chart value from the galvanized chart value and treat the result as the actual zinc thickness. Historical gauge allowances and a specific product’s coating requirement are different references.
On the order, identify the required thickness basis, coating designation and applicable product specification. If powder coating or paint is added later, identify which dimensions apply after that finish. See our guide to sheet metal finishes and dimensional considerations when coordinating the final coating requirement.
Check Thickness Before Approving a Substitution
A gauge chart establishes a nominal lookup value. It does not determine whether another material or thickness is acceptable for the part.
Before approving a change, review:
- Material specification: grade, temper or condition, and coating requirements.
- Assembly interfaces: slots, clips, fasteners and mating features that depend on sheet thickness.
- Formed geometry: whether the CAD thickness, bend assumptions and finished dimensions need revision.
- Process requirements: cut-edge condition, critical features and any additional operations.
- Acceptance: required thickness range, measurement basis and finished condition.
The sheet metal gauge alone cannot establish load capacity or a universal minimum bend radius. Those decisions require the material properties, geometry and application requirements. When choosing a cutting route, compare laser, plasma and waterjet cutting against the actual part requirements.
For incoming inspection, use a suitable calibrated thickness-measurement instrument and the method required by the product specification. Take readings on appropriate clean areas; burrs, local damage and coatings can affect what is measured. A close match to a chart value does not establish the material grade or replace the specified acceptance range.
Turn a Gauge Lookup into a Clear Fabrication RFQ
For custom sheet metal fabrication, send the part geometry with an explicit material and thickness requirement. A useful RFQ includes:
- Material grade and condition.
- Controlling thickness in inches or millimeters, with the applicable tolerance or specification.
- Part drawing and model or flat pattern, with revision identification.
- Critical formed dimensions, finish requirements and acceptance stage.
- Quantity and any approved material or thickness alternatives.
Use this sheet metal gauge chart to identify the reference value, then make the purchasing requirement explicit. Request a sheet metal fabrication quote with your drawing, material, decimal thickness and quantity so the proposed material and manufacturing scope can be assessed together.
