Steel Gauge Thickness Guide: MM Charts & Conversion Tables

Steel gauge actually refers to the standard thickness of a sheet metal which follows an inversely proportional relationship between the gauge and thickness; in which the gauge increases when the sheet metal’s thickness falls and vice versa.

Steel or Sheet Metal

Steel is an alloy made up of different kinds of elements; but iron presents the greatest value compared to other components such as carbon. Sheet metal on the other hand is basically metal designed into thin quantities used for metalworking. The customary range gauge of a metal sheet is from a scale of 35 going down to 6. Nevertheless, in some situations sheet metal’s thickness can vary significantly which is then called foil or leaf. Thickness that is more than 6mm or 0.25 inches is called plates. These materials can be usually seen in construction works and are used for metalworking. Most of the bits and pieces we see and purchase are consist of such material and are develop for different kind of purposes. By using specific tools, this steel sheet metal can be cut, bent and form into creative work of arts such as those of car frames and aircraft wing extensions.

The Steel Gauge Chart         

Most people working with steel sheet metals consult to a particular chart for reference when it comes to gauge number and thickness. This chart is usually called the Steel Gauge Chart. It practically gives you the figures which indicate the sheet metal’s gauge and thickness in millimeter, inches and even fractional regular measurements. Here are the following statistics that shows the close association of the gauge and thickness.

Gauge No.

Thickness

fraction

inch

mm

6

13/64

.2031

5.16

7

3/16

.1875

4.76

8

11/64

.1719

4.37

9

5/32

.1563

3.97

10

9/64

.1406

3.57

11

1/8

.1250

3.18

12

7/64

.1094

2.78

13

3/32

.0938

2.38

14

5/64

.0781

1.98

15

-

.0703

1.79

16

1/16

.0625

1.59

17

-

.0563

1.43

18

-

.0500

1.27

19

-

.0438

1.11

20

-

.0375

.953

21

-

.0344

.873

22

1/32

.0313

.794

23

-

.0218

.714

24

-

.0250

.635

25

-

.0219

.556

26

-

.0188

.478

27

-

.0172

.437

28

1/64

.0156

.396

29

-

.0141

.358

30

-

.0125

.318

31

-

.0109

.277

32

-

.0102

.259

33

-

.0094

.239

34

-

.0086

.218

35

-

.0078

.198

Chart link: http://www.offroaders.com/tech/steel-gauge-thickness.htm

It is clearly noted in the chart above that the connection between the gauge and thickness of sheet metals are opposite from each other.

Other Gauge Charts

 

ALUMINUM

STEEL

Difference in (mm)

Gauge

inch

mm

inch

mm

mm

3

.2294

5.827

.2391

6.073

0.246

4

.2043

5.189

.2242

5.695

0.506

5

.1819

4.620

.2092

5.314

0.694

6

.1620

4.115

.1943

4.935

0.82

7

.1443

3.665

.1793

4.554

0.889

8

.1285

3.264

.1644

4.176

0.912

9

.1144

2.906

.1495

3.797

0.891

10

.1019

2.588

.1345

3.416

0.828

11

.0907

2.304

.1196

3.030

0.726

12

.0808

2.052

.1046

2.657

0.605

13

.0720

1.829

.0897

2.278

0.449

14

.0641

1.628

.0747

1.897

0.269

15

.0571

1.450

.0673

1.709

0.259

16

.0508

1.290

.0598

1.519

0.229

17

.0453

1.151

.0538

1.367

0.216

18

.0403

1.024

.0478

1.214

0.19

19

.0359

0.912

.0418

1.062

0.15

20

.0320

0.813

.0359

0.912

0.099

21

.0285

0.724

.0329

0.836

0.112

22

.0253

0.643

.0299

0.759

0.116

23

.0226

0.574

.0269

0.683

0.109

24

.0201

0.511

.0239

0.607

0.096

25

.0179

0.455

.0209

0.531

0.076

26

.0159

0.404

.0179

0.455

0.051

27

.0142

0.361

.0164

0.417

0.056

28

.0126

0.320

.0149

0.378

0.058

29

.0113

0.287

.0135

0.343

0.056

30

.0100

0.254

.0120

0.305

0.051

31

.0089

0.226

.0105

0.267

0.041

32

.0080

0.203

.0097

0.246

0.043

33

.0071

0.180

.0090

0.229

0.049

34

.0063

0.160

.0082

0.208

0.048

35

.0056

0.142

.0075

0.191

0.049

Chart link: http://www.offroaders.com/tech/steel-gauge-thickness.htm

The chart above represents the different values of gauge and thickness in ferrous scales (example is steel) and non-ferrous scales (example is aluminum). Aluminum when compared to steel shows the same relationship of the gauge and the thickness; however, the ferrous gauges have a higher thickness value contrary to the non-ferrous gauges. And when you go up sequentially, you’ll definitely observe the alteration between the figures. Initially it gradually increases and then quickly changes in a more progressive way. As you can see, the difference on its entirety varies from one point to another.

The Conversion Table

This conversion table will show us the exact values in decimal inches for every gauge for sheet steel, galvanized steel, stainless steel, aluminum and both strip and tubing. This is very essential when working or dealing with different kinds of steel and making numerous objects from it.

Gauge

US Standard Gauge

Sheet Steel

Galvanized Steel

Stainless Steel

Aluminium

Strip & Tubing

(inches)

Gauge Decimal
(inches)

Gauge Decimal
(inches)

Gauge Decimal
(inches)

Gauge Decimal
(inches)

Gauge Decimal
(inches)

35

0.0078

0.0075

0.0078

0.0056

0.005

34

0.0086

0.0082

0.0086

0.0063

0.007

33

0.0094

0.0090

0.0094

0.0071

0.008

32

0.0102

0.0097

0.0102

0.0080

0.009

31

0.0109

0.0105

0.0109

0.0089

0.010

30

0.0125

0.0120

0.016

0.0125

0.0100

0.012

29

0.0141

0.0135

0.017

0.0141

0.0113

0.013

28

0.0156

0.0149

0.019

0.0156

0.0126

0.014

27

0.0172

0.0164

0.020

0.0172

0.0142

0.016

26

0.0188

0.0179

0.022

0.0187

0.0159

0.018

25

0.0219

0.0209

0.025

0.0219

0.0179

0.020

24

0.0250

0.0239

0.028

0.0250

0.0201

0.022

23

0.0281

0.0269

0.031

0.0281

0.0226

0.025

22

0.0313

0.0299

0.034

0.0312

0.0253

0.028

21

0.0344

0.0329

0.037

0.0344

0.0285

0.032

20

0.0375

0.0359

0.040

0.0375

0.0320

0.035

19

0.0438

0.0418

0.046

0.0437

0.0359

0.042

18

0.0500

0.0478

0.052

0.0500

0.0403

0.049

17

0.0563

0.0538

0.058

0.0562

0.0453

0.058

16

0.0625

0.0598

0.064

0.0625

0.0508

0.065

15

0.0703

0.0673

0.071

0.0703

0.0571

0.072

14

0.0781

0.0747

0.079

0.0781

0.0641

0.083

13

0.0938

0.0897

0.093

0.0937

0.0720

0.095

12

0.1094

0.1046

0.108

0.1094

0.0808

0.109

11

0.1250

0.1196

0.123

0.1250

0.0907

0.120

10

0.1406

0.1345

0.138

0.1406

0.1019

0.134

9

0.1563

0.1495

0.153

0.1562

0.1144

0.148

8

0.1719

0.1644

0.168

0.1719

0.1285

0.165

7

0.1875

0.1793

0.1875

0.1443

0.180

6

0.2031

0.1943

0.2031

0.1620

0.203

5

0.2188

0.2092

0.2187

0.1819

0.220

4

0.2344

0.2242

0.2344

0.2043

0.238

3

0.2500

0.2391

0.2500

0.2294

0.259

2

0.2656

0.2656

0.2576

0.284

1

0.2813

0.2812

0.2893

0.300

Conversion Table link: http://www.engineeringtoolbox.com/gauge-sheet-d_915.html

At this time, it is important that one must remember that in dealing with such conversion process it is always best to study first the type of steel being used. You should first find out whether the steel utilized was galvanized or its plain stainless or sheet steel. Conversion differs and depends on what type of gauge system want to use. There are actually two gauge systems that can be use: the US Standard Gauge System and the MSG system or also known as the Manufacturer’s Standard Gauge system. The US standard gauge system usually uses the value from 2, 1, 0, 2/0, 3/0, 4/0, 5/0, 6/0 or 7/0. MSG’s largest thickness in sheet steel is 3. In galvanized steel it is 8 and for stainless steel it is 6/0. Next step for our conversion process is to determine the exact thickness of the material you’re using in its specific gauge. By multiplying 25.4 to your measurements you are actually converting the units into millimeters.

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