Steel Gauge Conversion Chart

A Steel Gauge Conversion Chart is your guide for the material thickness. While these gauge numbers do not indicate a specific dimensional value, they range between 3-30. Standard gauge sizes were developed based on the weight of the sheet for a given material and the equivalent thicknesses.

Gauge is derived from and related to the French word 'jauge', meaning 'result of measurement'. This form of measurement originated in the British iron wire industry when there was no universal unit for thickness. The sizes of the gauge numbers were the result of the process of wire-drawing and the nature of iron itself.

Gauges were measured and described in fractions of an inch during the 19th century. Artisans at the time found gauge sizes to be convenient, thus furthered its use. Moving into the 20th century, the gauge was to be replaced by the International System of Units, which ultimately did not occur.

KEY POINTS

  1. Steel Gauge Conversion Chart
  2. What are Gauge Sizes?
  3. What is the Gauge of a Tube?
  4. Pipe or Tube: What is the difference?
  5. What is Really Length?
  6. How is Weight Defined?
  7. What is Tensile Strength?

1. Steel Gauge Conversion Chart

The Standard Gauge Chart provides the thicknesses for Stainless Steel, Galvanized Steel, Sheet Steel and Aluminum. Gauge sizes are numbers that indicate the thickness range of a piece of metal, with a higher number referring to a thinner sheet. The equivalent thicknesses differ for each gauge size standard depending on the material.

Standard and metric conversion tables are commonly used in the Steel industry. Use the chart below to determine the equivalent thickness, in inches or millimeters, for a gauge number from the selected gauge size standard.

Steel Gauge Conversion Chart
Stainless Steel Galvanized Steel Sheet Steel Aluminum
Gauge Frac Inches mm Inches mm Inches mm Inches mm
30 0.0125 0.33 0.0157 0.40 0.0120 0.30 0.0100 0.25
29 0.0141 0.36 0.0172 0.44 0.0135 0.34 0.0113 0.29
28 1/64 0.0156 0.41 0.0187 0.47 0.0149 0.38 0.0126 0.32
27 0.0172 0.43 0.0202 0.51 0.0164 0.42 0.0142 0.36
26 0.0187 0.48 0.0217 0.55 0.0179 0.45 0.0159 0.40
25 0.0219 0.56 0.0247 0.63 0.0209 0.53 0.0179 0.46
24 0.025 0.64 0.0276 0.70 0.0239 0.61 0.0201 0.51
23 0 0281 0.71 0.0306 0.78 0.0269 0.68 0.0226 0.58
22 1/32 0.0312 0.79 0.0336 0.85 0.0299 0.76 0.0253 0.64
21 0 0344 0.86 0.0366 0.93 0.0329 0.84 0.0285 0.71
20 0.0375 0.95 0.0396 1.01 0.0359 0.91 0.0320 0.81
19 0.0437 1.10 0.0456 1.16 0.0418 1.06 0.0359 0.91
18 0.0500 1.27 0.0516 1.31 0 0478 1.21 0.0403 1.02
17 0.0562 1.40 0.0575 1.46 0.0538 1.37 0.0453 1.10
16 1/16 0.0625 1.59 0.0635 1.61 0.0598 1.52 0.0508 1.29
15 0.0703 1.80 0.0710 1.80 0.0673 1.71 0.0571 1.40
14 5/64 0.0781 1.98 0.0785 1.99 0.0747 1.90 0.0641 1.63
13 3/32 0.094 2.40 0.0934 2.37 0.0897 2.28 0.072 1.80
12 7/64 0.1094 2.78 0.1084 2.75 0.1046 2.66 0.0808 2.05
11 1/8 0.1250 3.18 0.1233 3.13 0.1196 3.04 0.0907 2.30
10 9/64 0.1406 3.57 0.1382 3.51 0.1345 3.42 0.1019 2.59
9 5/32 0.1563 3.97 0.1532 3.89 0.1495 3.80 0.1144 2.91
8 11/64 0.1719 4.37 0.1681 4.27 0.1644 4.18 0.1285 3.26
7 3/16 0.1875 4.76 0.1793 4.55 0.1443 3.67
6 13/64 0.2031 5.16 0.1943 4.94 0.162 4.10
5 7/32 0.2187 5.55 0.2092 5.31 0.1819 4.62
4 15/64 0.2344 5.95 0.2242 5.69 0.2043 5.19
3 1/4 0.25 6.35 0.2391 6.07 0.2294 5.83

2. What are Gauge Sizes?

Gauge sizes are numbers that indicate the thickness of a piece of sheet metal or the thickness of a tube, with a higher number referring to a thinner thickness. The equivalent thicknesses differ for each gauge size standard, which was developed based on the weight of a given material.

3. What is the Gauge of a Tube?

Tube Wall Thickness is Gauge with the lower the gauge number, the thicker the wall thickness of the tube.

4. Pipe or Tube: What is the difference?

Both pipe and tube have two critical measurements: The outside diameter (O.D.) and the wall thickness. The difference is the terminology used when calling out the proper "name" when referring to the size of material and wall thicknesses. Tubes use gauge while pipe uses schedule for wall thickness. A tube's name would be 1.5" gauge 10, while a pipe's name is schedule 5 1.5".

5. What is Really Length?

Length is a measure of distance as defined in the International System of Quantities (ISQ). This term is often used in physics and modern science. The use of basic quantities such as length and mass, and the relationships between those quantities are common. This relationship underlies the International System of Units but doesn't determine the units of measurement used for the quantities.

Various terms for the length include height, width and depth. Height is used when there is a base from which a vertical measurements can be taken. Width usually refers to a shorter dimension and Depth is used for the third dimension of a three dimensional object.

This chart shows the relationship between standard and metric system of measurement is standard across all industry.

Meter Millimeter Inch Feet Yard
m mm in
(“)
ft yd
1 1000 39.3700 3.2808 1.093613
0.001 1 0.03937 0.00328 0.001093
0.0254 25.4 1 0.08333 0.08777
0.3048 304.8 12 1 0.333
0.9144 914.4 36 3 1

6. How is Weight Defined?

The weight of an object is the force acting on the object due to gravity as defined in the science and engineering community. While weight and mass are scientifically distinct quantities there terms are often mixed with each other in everyday use. Weight per unit area can also be seen in pounds per square foot or kilograms per square meter.

The unit of measurement for weight is force. In the International System of Units (SI) it is the newton. In the metric system of measurement weight is defined as Kilogram-force which is the force exerted by Earth's gravity at sea level on one kilogram of mass. Pound of force or pound-force in English Engineering units. Pound-Force is defined as gravitational force applied on a mass of one pound at sea level.

Building safety specifications are commonly defined in kilonewtons. This includes the holding values of fasteners, Earth anchors, Railing loads and other items used in the building industry as well as working loads in tension and in shear. The chart below show the relation between common units used in industry.

Kilogram Ton Pound
Kg Ton Lb
1 0.001 2.2045
1000 1 2204
0.4536 0.000453 1

7. What is Tensile Strength?

The maximum stress a material can withstand while being stretched or pulled before breaking is referred to as tensile strength. This is not dependent in size of the material. Tensile strength of the material is used in the engineering calculations in the construction industry.

Factors such as material preparation, surface defects and the environment do effect tensile strength. Quality in the manufacturing process is important in minimizing these effects.

The strength per square inch or Tensile Strength is shown in KSI, PSI, and Megapascal units.

Pound/Square Inch 1000 Pound/Square Inch Megapascal
PSI KSI Mpa
1 0.001 0.006895
1000 1 6.895
145.0326 0.1450326 1