Sheet Metal Gauge Chart

Sheet metal gauge chart showing SWG (Standard Wire Gauge) conversions to millimetres and inches, covering a full range from thick plate to fine sheet.

This reference is used by fabricators, designers and engineers to quickly compare gauge sizes and specify accurate material thicknesses across copper, brass, stainless steel, aluminium and mild steel.

For clarity when ordering or manufacturing, we always recommend working in millimetres (mm), with gauge used as a secondary reference.

How to Use This Sheet Metal Gauge Chart

This sheet metal gauge chart converts Standard Wire Gauge (SWG) values into millimetres and inches, allowing quick comparison between traditional gauge sizes and modern metric measurements.

SWG – traditional UK gauge system (lower = thicker)
Millimetres (mm) – precise measurement used in fabrication
Inches – imperial reference for legacy drawings

For projects requiring accurate thickness control and clean edges, precision cutting is typically carried out using CNC processes such as precision sheet metal laser cutting, delivering consistent results across both one-off and production work.

While gauge is still commonly used in specifica

Natural Copper

Natural Brass

Aluminium Natural

Aluminium Brushed

Aluminium Stucco

Brushed Brass

Brushed Copper

Stainless Steel 430 Brushed

Stainless Steel Mirror Sheet

Natural Zinc

What Is Sheet Metal Gauge?

Sheet metal gauge is a numerical system used to describe the thickness of metal sheet. In the Standard Wire Gauge (SWG) system, lower numbers represent thicker material, while higher numbers represent thinner material.

For example, 10 SWG is much thicker than 30 SWG. This can be confusing if you are used to working in millimetres, which is why gauge charts are commonly used to convert traditional gauge sizes into metric and imperial measurements.

10 SWG is approximately 3.25mm
20 SWG is approximately 0.91mm
30 SWG is approximately 0.32mm

For example, 1mm sheet metal is approximately 19–20 SWG, depending on the material.

Because gauge systems can vary depending on material and region, most modern fabrication, laser cutting and sheet metal supply work is specified in millimetres (mm). Gauge remains useful as a reference, especially when reading older drawings, legacy specifications or trade documents.

Sheet metal is available in a wide range of thicknesses and finishes, with options

SWG	INCH	MM	SWG	INCH	MM
7/0	0.500	12.70	23	0.024	0.61
6/0	0.464	11.79	24	0.022	0.56
5/0	0.432	10.97	25	0.020	0.51
4/0	0.400	10.16	26	0.018	0.46
3/0	0.372	9.45	27	0.016	0.42
2/0	0.348	8.84	28	0.015	0.38
1/0	0.324	8.24	29	0.014	0.35
1	0.300	7.62	30	0.012	0.32
2	0.276	7.01	31	0.012	0.30
3	0.252	6.40	32	0.011	0.27
4	0.232	5.89	33	0.010	0.25
5	0.212	5.39	34	0.009	0.23
6	0.192	4.88	35	0.008	0.21
7	0.176	4.47	36	0.008	0.19
8	0.160	4.06	37	0.007	0.17
9	0.144	3.66	38	0.006	0.15
10	0.128	3.25	39	0.005	0.13
11	0.116	2.95	40	0.005	0.12
12	0.104	2.64	41	0.004	0.11
13	0.092	2.34	42	0.004	0.10
14	0.080	2.03	43	0.004	0.09
15	0.072	1.83	44	0.003	0.08
16	0.064	1.63	45	0.003	0.07
17	0.056	1.42	46	0.002	0.06
18	0.048	1.22	47	0.002	0.05
19	0.040	1.02	48	0.002	0.04
20	0.036	0.91	49	0.001	0.03
21	0.032	0.81	50	0.001	0.03
22	0.028	0.71

Understanding Zinc Gauge Chart

Zinc uses a different gauge system (ZG), where higher numbers indicate thicker material — the opposite of SWG.

Zinc gauge is not commonly used in general sheet metal fabrication, but it can still appear in older specifications, roofing references and some zinc sheet descriptions. For this reason, it is useful to understand how zinc gauge relates to modern metric thicknesses.

For reference, here is a selection of zinc sheet gauges (ZG) and their nearest corresponding thickness in millimetres:

6 ZG = 0.3mm
7 ZG = 0.35mm
8 ZG = 0.40mm
9 ZG = 0.45mm
10 ZG = 0.5mm
11 ZG = 0.6mm
12 ZG = 0.7mm
13 ZG = 0.8mm
14 ZG = 0.9mm
15 ZG = 1.0mm
16 ZG = 1.1mm
17 ZG = 1.2mm
18 ZG = 1.4mm
19 ZG = 1.5mm
20 ZG = 1.8mm
21 ZG = 2.0mm
22 ZG = 2.3mm
23 ZG = 2.5mm
24 ZG = 3.0mm

At Metal Sheets Ltd, we recommend specifying zinc sheet thickness in millimetres wherever possible, as this avoids confusion between zinc gauge and other gauge systems.

View our zinc sheet range or visit our wood screw gauge chart for another useful sizing reference.

Sheet Metal Supply & Fabrication Services

Metal Sheets Ltd supplies a wide range of sheet metals in different sizes, thicknesses and finishes, including copper sheet, brass sheet, zinc sheet, aluminium sheet and stainless steel sheet.

We supply full sheets and part sheets, with material sizes depending on the metal type and finish selected. Many of our copper, brass and zinc sheets are available in large formats up to approximately 3000mm long, while aluminium, stainless steel and Corten steel sheets are available in a range of practical stock sizes for fabrication, interiors, signage and architectural projects.

Our in-house capabilities include guillotine cutting, forming, welding and fabrication, allowing us to support bespoke interior features, architectural metalwork and commercial projects from concept through to finished installation.

For precision-cut components, profiles and production work, our dedicated trade division MS Laser Services provides specialist precision sheet metal laser cutting for thin-gauge materials

For smaller cut-to-size orders and part sheets, visit our Metal Offcuts store. For bespoke fabrication or project enquiries, please contact Metal Sheets Ltd.

Enquiry

If you have a project requirement and would like to make some initial enquiries, please get in touch. Please contact us via email sales@metalsheets.co.uk, give us a call on 0151 526 4777, or fill the contact form. We’re looking forward to hearing from you.
Alternatively, shop safely and securely and purchase sheet metals via this website.