SWG to mm converter: British wire gauge
SWG is common for British and Indian wire, craft wire and welding wire; this tool gives its metric diameter.
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How to use it
- Enter swg gauge.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Each gauge has a fixed diameter in inches in the Imperial Standard Wire Gauge (BS 3737:1964). Diameter (mm) = inches × 25.4, area = π / 4 × diameter².
Example
Inputs: SWG gauge = 16. Result: Diameter: 1.6256 mm; Diameter in inches: 0.064 in; Cross-section area: 2.0755 mm².
Limits and caveats
- SWG differs from AWG; the same number does not give the same diameter.
- Values are nominal; standards allow small manufacturing tolerances.
Questions about this tool
What is the diameter of 16 SWG?
It is 0.064 in, which is 1.626 mm.
Is SWG the same as BWG?
No. BWG is the older Birmingham gauge with different values; SWG is the Imperial Standard Wire Gauge set in 1883.
Where is SWG used today?
For craft wire, springs, welding wire and some cable in the UK, India and Pakistan.