📏 Wire Gauge Reference Chart

Select a wire gauge (AWG) commonly used in jewelry making to see its diameter in millimeters and inches.

Wire gauge (AWG)

The formula behind the chart

AWG is not a lookup table but a geometric series, and the page computes it rather than storing it. Diameter in millimetres is:

d = 0.127 × 92^((36 - AWG) / 39)

The anchor is 36 AWG at exactly 0.127 mm, which is 0.005 in, and the ratio 92 spreads 39 steps between the ends of the scale. For 20 AWG the exponent is 16/39, giving 0.812 mm, or 0.0320 in. Because it is geometric, six gauge numbers double or halve the diameter (92^(6/39) = 2.005) and three gauge numbers double the cross-sectional area. Bigger number, thinner wire, every time.

Which gauge for which job

AWG	mm	Typical use
14	1.628	Bangles, heavy jump rings
16	1.291	Sturdy frames, clasps
18	1.024	Ear wires, headpins
20	0.812	General wrapping, links
24	0.511	Wrapping small beads
28	0.321	Weaving, coiling, pearls

Bead holes decide the ceiling. A drilled pearl at 0.5 mm takes 24 AWG and nothing thicker; a standard 0.7 mm hole will just pass 22 AWG at 0.644 mm.

This is AWG, the American scale. British SWG numbers do not match: SWG 20 is 0.914 mm against AWG 20 at 0.812, a difference big enough to jam a bead. Temper is separate again - dead soft, half hard and hard 20 AWG are all 0.812 mm.

Frequently asked questions

What is 20 gauge wire in mm?

0.812 mm, or 0.0320 in. It is the usual all-purpose jewellery wire, stiff enough to hold a wrapped loop and soft enough to bend with pliers.

Is 18 gauge thicker than 20 gauge?

Yes. The numbers run backwards: 18 AWG is 1.024 mm and 20 AWG is 0.812 mm. Each step down adds about 12 per cent of diameter.

What gauge wire is best for ear wires?

20 or 21 AWG, 0.812 to 0.723 mm, in half hard temper. Thinner bends out of shape in wear, and 18 AWG at 1.024 mm is about the limit a standard piercing takes comfortably.