Spring Wire Gauge (SWG) Chart — SWG to mm & inch
Quick answer: SWG (Standard Wire Gauge) is a wire-size scale where a higher number means thinner wire — for example SWG 14 is 2.032 mm (0.080 in) and SWG 20 is 0.914 mm (0.036 in).
By Gurudatta Trading Co., Mumbai · Updated 2026-09-28
SWG to mm and inch table
| SWG | mm | inch |
| 8 | 4.064 | 0.1600 |
| 9 | 3.658 | 0.1440 |
| 10 | 3.251 | 0.1280 |
| 11 | 2.945 | 0.1159 |
| 12 | 2.642 | 0.1040 |
| 13 | 2.337 | 0.0920 |
| 14 | 2.032 | 0.0800 |
| 15 | 1.829 | 0.0720 |
| 16 | 1.626 | 0.0640 |
| 17 | 1.422 | 0.0560 |
| 18 | 1.219 | 0.0480 |
| 19 | 1.016 | 0.0400 |
| 20 | 0.914 | 0.0360 |
| 21 | 0.813 | 0.0320 |
| 22 | 0.711 | 0.0280 |
| 23 | 0.610 | 0.0240 |
| 24 | 0.559 | 0.0220 |
| 25 | 0.508 | 0.0200 |
| 26 | 0.457 | 0.0180 |
| 27 | 0.417 | 0.0164 |
| 28 | 0.376 | 0.0148 |
| 29 | 0.345 | 0.0136 |
| 30 | 0.315 | 0.0124 |
How to use this chart for springs
Spring drawings normally state wire diameter in mm. Measure the wire with a micrometer, then match it to the nearest SWG value above. Wire diameter directly controls spring stiffness: because rate depends on the fourth power of wire diameter, a small change in gauge changes load a lot. Check your design in our spring rate calculator.
SWG differs from AWG and Birmingham (BWG) gauges, so always confirm the gauge system, or better, state the diameter in millimetres.
Need springs made to your specification?
Gurudatta Trading Co. (Mumbai, since 2000, ISO 9001:2015) manufactures compression, extension and torsion springs to drawing or sample. Use the free Spring Rate Calculator or message us on WhatsApp.
FAQs
What is SWG 14 in mm?
SWG 14 is 2.032 mm (0.080 inch).
Is a higher SWG number thicker or thinner?
Thinner. As the SWG number increases, wire diameter decreases.
Is SWG the same as AWG?
No. SWG (British Standard Wire Gauge) and AWG (American Wire Gauge) use different diameters for the same number, so specify wire size in mm.