Jewelry Gauge Converter
Convert jewelry gauge numbers to diameter in mm and find out which piercings they suit.
How to use this tool
- Enter gauge in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your diameter and the full breakdown beneath it.
Look up the diameter in millimetres for any jewelry gauge and find which piercings it is used for.
Formula
Jewelry gauge → diameter is a fixed lookup table (Body Jewelry Standard / BWG derivative):
20g = 0.81 mm, 18g = 1.02 mm, 16g = 1.29 mm, 14g = 1.63 mm, 12g = 2.05 mm, 10g = 2.59 mm, 8g = 3.26 mm
Each 2-gauge step increases diameter by approximately 26% (a geometric progression similar to AWG).
How it works
Jewelry gauge numbers follow a system derived from the Brown and Sharpe wire gauge, where a smaller gauge number indicates a larger diameter — the same inverse relationship as AWG wire. Diameter values are fixed industry standards stored in a lookup table; they are not calculated from a formula. A common mistake is confusing jewelry gauge with gauge in other contexts: a gauge-18 sewing needle, gauge-18 hypodermic needle, and gauge-18 piercing jewellery are all different sizes because each industry uses its own gauge standard, so always verify the system before purchasing body jewellery or needles.
Worked example
Looking up diameter and common uses for 18-gauge jewelry
- Gauge = 18.
- Look up gauge 18 in the jewelry gauge table.
- Diameter: 1.02 mm.
- Common uses: Standard piercings (helix, nostril, standard ear lobe).
Diameter: 1.02 mm | Common Uses: Standard piercings
Common mistakes to avoid
- Assuming jewelry gauge and AWG wire gauge have the same diameter values -- they use different standards; an 18g jewelry gauge is 1.02 mm while AWG 18 is 1.024 mm (nearly identical by coincidence), but they diverge at other sizes.
- Buying jewelry in the wrong gauge for a healed piercing -- a fresh piercing is typically done at 16g or 14g; downsizing too quickly to 18g in a cartilage piercing before full healing can cause irritation.
- Confusing gauge number direction -- like AWG, jewelry gauge is a reverse scale; 20g (0.81 mm) is thinner than 10g (2.59 mm).
Key terms
- Jewelry gauge
- A numbering system for body jewellery wire thickness derived from wire gauge standards; a lower gauge number means a thicker piece of jewellery, and a higher number means thinner.
- Gauge stretching
- The practice of progressively increasing the size of a piercing over time using larger-gauge jewellery; the process requires patience and sequential steps to avoid tearing tissue.
- Implant-grade material
- Jewellery materials certified safe for long-term skin contact (e.g. implant-grade titanium ASTM F136, surgical steel ASTM F138); the gauge tells you thickness but does not guarantee material safety.
- Gauge vs mm
- Because gauge numbers are non-linear and confusing, many professional piercers quote sizes directly in millimetres; 18g = 1.02 mm and 16g = 1.29 mm are the most common starting sizes for new piercings.
Frequently asked questions
- What gauge is a standard earring?
- Most standard earrings are 20G (0.81 mm). Freshly pierced ear lobes are typically done at 18G (1.02 mm).