Wire Gauge Calculator
AWG to millimetres, and what each gauge suits.
Convert jewellery wire between American Wire Gauge and millimetres, with what each gauge is typically used for.
Diameter
0.812 mm
20 AWG
The scale runs backwards — a higher number is thinner wire — and it is geometric, so six gauge numbers roughly halve the diameter. Hardness matters as much as gauge: dead soft, half hard and full hard behave completely differently at the same thickness.
How the Wire Gauge Calculator works
American Wire Gauge runs backwards — a higher number is thinner wire — and it is geometric rather than linear, so the steps are not even. Twenty gauge is 0.81 mm and twenty-six is 0.40, so six gauge numbers halve the diameter. That relationship is worth knowing because it means gauge differences matter far more at the thin end.
Also known as: AWG converter · jewellery wire gauge chart
A geometric scale that runs backwards
American Wire Gauge numbers the drawing operations used to reduce the wire, so a higher number means more passes through the die and a thinner wire. The formula is 0.127 × 92^((36 − gauge) ÷ 39) millimetres.
Because it is geometric rather than linear, the steps are not even. Six gauge numbers roughly halve the diameter: 14 gauge is 1.63 mm, 20 is 0.81 and 26 is 0.40. The same six-number gap means a much smaller absolute change at the thin end than at the thick.
That matters when substituting. Going from 20 to 22 gauge is a 20% reduction in diameter but a 36% reduction in cross-sectional area, and the wire's stiffness falls faster still.
A worked example
A pattern calls for 20 gauge for earwires. That is 0.81 mm — firm enough to hold its shape through an ear without bending, thin enough to be comfortable.
Substituting 22 gauge at 0.64 mm looks like a small change and produces earwires that deform in a pocket. Substituting 18 gauge at 1.02 mm makes them uncomfortably thick for most piercings. Two gauges either way is a real difference in function, not a rounding.
Where the answer misleads
Hardness matters at least as much as gauge and the number says nothing about it. Dead soft wire of a given gauge shapes easily and holds nothing; full hard holds a spring and work-hardens to cracking if overworked; half hard sits between and suits most wire wrapping. The same 20 gauge in three hardnesses behaves like three different materials.
Metal matters too. Twenty gauge sterling and twenty gauge copper have identical diameters and quite different stiffness, and sterling work-hardens as you form it while copper stays soft much longer.
Finally, AWG is not the only gauge system. British Standard Wire Gauge differs at most sizes, and some European suppliers sell by millimetre only. Converting between AWG and SWG by assuming they match is a common source of wire that is the wrong thickness.
Frequently asked questions
What gauge wire should I use for jewellery?
Roughly: 26 to 28 for wrapping and weaving, 24 for stringing small beads, 20 to 22 for earwires and links, 18 for jump rings and frames, and 16 or thicker for bangles and structural work.
Why is a higher gauge number thinner?
The scale counts drawing operations — the number of times the wire was pulled through a die to reduce it — so more passes means a higher number and a thinner wire. It is the same logic that makes UK knitting needle numbers run backwards.
How do I convert AWG to millimetres?
The formula is 0.127 × 92^((36 − gauge) ÷ 39). It is a geometric series, which is why the millimetre steps get smaller as the gauge number rises.
Does hardness matter as much as gauge?
Often more. Dead soft, half hard and full hard wire of the same gauge behave completely differently: dead soft shapes easily and holds nothing, full hard holds a spring and cracks if overworked. Half hard suits most wire wrapping.