Gauge to mm
Conversion Hub

Most gauge systems were created long before metric units. Their numbering runs in reverse. A lower gauge means a thicker material and a higher gauge means a thinner one. This applies to wire, sheet metal, needles, piercing jewelry, plastic film, and more.

No. Gauge is not universal. AWG, SWG, BWG, medical needle gauge, piercing gauge, plastic film gauge, and sheet metal gauge all use separate charts. The same gauge number can represent completely different sizes in each system.

It depends on the product. Electrical wire usually uses AWG, mesh and some metal tubing use SWG or BWG, medical needles use the medical gauge system, jewelry uses piercing gauge sizes, plastic film uses film gauge, and sheet metal uses its own gauge charts. The product label or spec sheet usually indicates the system.

Yes. Every gauge system can be converted to millimeters, but you must use the correct chart for the system. AWG has a formula. SWG, BWG, sheet metal gauge, plastic film gauge, medical gauge, and piercing gauge all rely on reference tables.

Because they belong to different gauge systems. For example, 18 gauge wire, 18 gauge sheet metal, 18 gauge needle, and 18 gauge piercing jewelry are all different sizes. The number alone does not determine thickness unless you know the system behind it.

Only AWG uses a mathematical formula. Other systems, like sheet metal gauge, SWG, BWG, plastic film gauge, and needle gauge, are based on fixed lookup tables. There is no single formula that fits every gauge type.

Gauge is a numbering system. Thickness and diameter are physical measurements. Leather uses weight (ounces), which converts into thickness. Wire uses diameter. Sheet metal, film, and pipe walls use thickness. Understanding the material tells you how gauge should be interpreted.

Most charts list standard nominal values. Actual products can vary slightly because of manufacturing tolerances, coatings, insulation, finishing, or compression. Always check the supplier’s specs for precision-critical work.

Yes, but it is usually an approximation. A mm-to-gauge match is only exact if the size falls directly on a standard gauge value. When it lands between two gauge values, round to the closest standard size or list the exact mm value.

Both use a gauge numbering system, but they are not the same. A 20g medical needle does not match a 20g piercing jewelry size. Each system was developed separately and has its own diameter chart.

No. Gauge refers to the core material, not the added layers. For example, wire insulation does not change AWG, paint does not change sheet metal gauge, and polished or compressed leather still follows its original ounce-to-mm thickness.

AWG and medical gauge are widely used. Sheet metal gauge, SWG, and BWG still appear in older drawings and some industries. Plastic film gauge is still common in packaging. Leather ounces remain standard in leathercraft. Metric units are growing in popularity because they avoid confusion.

Yes. Some manufacturers use slightly different tolerances. Different countries also follow different legacy gauge systems. This is why mm or inches are often preferred for accuracy and global compatibility.

Use gauge when referencing older drawings, industry standards, or product listings that still use gauge numbers. Use millimeters when precision matters or when ordering internationally. Listing both values prevents mistakes.