Gauge is the thickness of the jewelry which is based on the American Standard Wire Gauge. It starts at 36g and goes to 0000g. The larger the number the thinner the wire will be. When choosing a gauge to be pierced at, the piercer must decide which is thick enough to reduce migration and tearing but thin enough to not add too much weight. See gauge to mm/inch conversion chart below for more information.
| Gauge | Metric - Millimeters(mm) | Inches |
| 24g | 0.5mm (0.55mm) | 0.02" |
| 22g | 0.7mm | 0.025 |
| 20g | 0.8mm (0.82mm) | 1/32" / 0.032" |
| 18g | 1.0mm (1.024mm) | 5/128" / 0.040" |
| 16g | 1.2mm/1.3mm (1.33mm) | 3/64" / 0.051" |
| 14g | 1.6mm (1.63mm) | 1/16" / 0.064" |
| 12g | 2mm (2.06mm) | 5/64" / 0.081" |
| 10g | 2.6mm (2.60mm) | 3/32" / 0.102" |
| 8g | 3.2mm (3.25mm) | 1/8" / 0.128" |
| 6g | 4mm (4.12mm) | 5/32" / 0.162" |
| 4g | 5mm (5.18mm) | 3/16" / 0.204" |
| 2g | 6mm (6.53mm) | 1/4" / 0.257" |
| 0g | 8mm (8.26mm) | 1/3" / 0.325" |
| 00g | 9mm (9.55mm) | 3/8" / 0.365" |
| 000g | 11mm (11.11mm) | 7/16" / 0.437" |
| 0000g | 12mm (12.71mm) | 1/2" / 0.51" |
| 14 mm | 9/16" | |
| 16 mm | 5/8" | |
| 19 mm | 3/4" | |
| 22 mm | 7/8" | |
| 25 mm | 1" | |
| 29 mm | 1 1/8" | |
| 32 mm | 1 1/4" | |
| 35 mm | 1 3/8" | |
| 38 mm | 1 1/2" | |
| 41 mm | 1 5/8" | |
| 44 mm | 1 3/4" | |
| 48 mm | 1 7/8" | |
| 51 mm | 2" |
This printable GAUGE SIZE CHART in Adobe Acrobat pdf format can be used to approximate size once printed. You can also use a ruler for length measurements.
For measuring jewelry that you already wear to find out the gauge, take a piece of string or dental floss and wrap it around the item at the part you want to measure, clipping it so that the ends meet to form a perfect circle around the plug. Next, lay the floss flat against a millimeter ruler and measure its approximate length in millimeters. Now you have the circumference of the jewelry. To get the gauge size (or diameter/thickness), divide the number you’ve reached by 3.14 and round.
For example: your string measures just over ten millimeters. 10 millimeters divided by 3.14 (Pi), equals 3.1847. Round 3.1847 to 3.2. Check the chart above and you’ll see that 3.2 millimeters is an 8 gauge.