Wire Gauge Comparison Chart

Wire is sized using a handful of different gauge systems that each grew out of a different national wiremaking tradition, and none of them line up neatly with the others — and confusingly, most gauge systems run backwards, with a higher gauge number meaning a thinner wire. AWG (American Wire Gauge) is the standard in the US, SWG (Standard Wire Gauge) is the older British system, and metric sizing simply states the diameter in millimetres directly. The chart below cross-references AWG, SWG, and metric sizes so you can convert between them, along with the nearest matching drill size for each — useful when you need a hole that's a good sliding or clearance fit on a particular wire.

Dimensions shown are in mm and Inches, if you wish to convert, please use our universal converter.

Wire Gauge Comparison Chart

ISO WIRE GAUGE EQUIVALENTS

RELATED PAGES

• Drill Size Charts
• Sheet Metal Gauge Chart
• Unit Conversion Calculator
• Engineering Glossary — Wire Gauge

FREQUENTLY ASKED QUESTIONS

Why does a bigger gauge number mean a thinner wire?

Both AWG and SWG originated from the number of times a wire had to be drawn through progressively smaller dies to reach its final size — more draws (a higher number) produced a thinner wire, and the numbering has stuck ever since.

Are AWG and SWG sizes interchangeable?

No — a given gauge number represents a different actual diameter in each system, and the difference becomes more significant at larger wire sizes. Always convert using a chart like the one above rather than assuming the same number means the same size.

How do I pick a drill size to match a wire diameter?

Use the drill size listed alongside the wire gauge you need. For a sliding fit (e.g. threading wire through a hole), choose a drill very close to the bare wire diameter; for a looser clearance fit, go up a size or two. Remember that insulated wire measures larger than the bare conductor size shown here — check the actual insulated diameter with a micrometer if it needs to pass through a tight hole.

Do these sizes account for wire insulation?

No, the diameters given are for the bare, uninsulated conductor. Insulation thickness varies by manufacturer and insulation type, so measure the actual insulated wire directly if that dimension matters for your application.