What is SWG (Standard Wire Gauge)?

Standard Wire Gauge (SWG) is the British Imperial system for specifying wire diameter, defined in BS 3737. Confusingly, a higher gauge number means a thinner wire — so 28 SWG is much finer than 18 SWG. SWG is widely used in the UK for craft wire, jewellery wire, and electrical wire. The American system (AWG) uses different numbers and should not be confused with SWG.

What SWG wire is best for jewellery making?

For structural frames and thick bangles, 16–18 SWG is commonly used. For wrapping, coiling and general wirework, 20–24 SWG is the most popular range. For fine detail work, finishing wraps and delicate weaves, 26–28 SWG is ideal. Copper and silver are the most popular jewellery wire materials; aluminium is lighter and more economical for practice and large-scale work.

What is the difference between copper, silver and aluminium wire for jewellery?

Copper is affordable, easy to work with, and develops a warm patina over time. It is excellent for practising and for everyday jewellery. Fine silver (99.9%) and sterling silver (92.5%) are the premium choices — tarnish-resistant, hypoallergenic and ideal for sale items. Aluminium wire is very lightweight, does not tarnish, and is cost-effective for larger or wearable art pieces, though it cannot be soldered as easily as copper or silver.

How do I convert SWG to mm or AWG?

Each SWG gauge has a fixed diameter in millimetres as defined in the British standard. For example, 24 SWG = 0.559 mm and 20 SWG = 0.914 mm. AWG (American Wire Gauge) uses a different scale — 24 AWG = 0.511 mm, which is close but not identical to 24 SWG. Always check which gauge system your wire supplier uses before ordering.

Why does wire weight matter for jewellery?

Wire weight affects the wearability and shipping cost of finished pieces. Earrings in particular need to be light enough to be comfortable — heavy earrings can cause ear lobe stretching over time. Aluminium wire is around three times lighter than copper or silver for the same gauge and length, making it ideal for large statement earrings or sculptural pieces.

CraftCalcs

Wire Gauge Calculator — SWG Diameter, Weight & Cost

Calculate wire diameter, weight, electrical resistance and cost estimate for craft and jewellery wire by Standard Wire Gauge (SWG).

Wire Gauge (SWG)Standard Wire Gauge — higher numbers are thinner; 20–24 SWG is most popular for jewellery making

Wire Length

Total length of wire you are working with or ordering — enter the full reel or project length

MaterialWire material — affects density, weight, electrical properties and price estimate

How We Calculate This

This calculator uses the Standard Wire Gauge (SWG) diameter table (BS 3737) to look up the exact wire diameter, then calculates physical and electrical properties from first principles.

Cross-sectional area

Area = π × (diameter / 2)²

Weight

Weight (g) = Area (mm²) × Length (m) × Density (g/cm³) × 0.001

Resistance

Resistance (Ω) = Resistivity (Ω·mm²/m) × Length (m) / Area (mm²)

Price estimates are based on typical UK retail craft wire prices by gauge range and material. Use the custom price option for accuracy with your specific supplier.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.