Aluminum sheet thickness is usually expressed in the United States using gauge (gauge), in the international are more commonly used millimeters (mm) as a unit. Gauge is a traditional unit of expressing the thickness of the material, but it is not a linear or direct unit, it is not directly equivalent to the specific thickness value, but according to different materials and industry standards and changes, the thickness of different metal materials (e.g. aluminum, steel, etc.) may vary under the same gauge.

The relationship between gauge value and thickness is non-linear, that is, the larger the gauge value indicates that the material is thinner; while the gauge value is smaller indicates that the material is thicker. For aluminum sheet, commonly used conversion tables provide an approximate aluminum sheet gauge to mm conversion.

In order to convert gauge to millimeters, a specific conversion table or formula needs to be used. Note, however, that different industries or standards may have different conversion tables. Below is an approximate conversion relationship from aluminum sheet gauge to millimeters for a common gauge (this is an example and does not apply in all cases):

For more accurate conversions, it is recommended to consult industry-specific or standard gauges to millimeters conversion tables or use an online conversion tool.

It is also important to note that the actual thickness may vary due to errors in the manufacturing and measuring process. Therefore, when purchasing aluminum sheet, it is best to check with your supplier for specific thickness specifications and tolerance ranges.