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Big Blue Saw Blog

How Thick is a Steel Gauge? And Why is My Part 0.002 Inches Too Thin?

When you order custom waterjet cut cold rolled steel on the Big Blue Saw website, you've got a choice of several different thicknesses for your parts. We offer the following thicknesses, from 0.0239 inch all the way up to 0.135 inch:

0.0239, 0.0299, 0.0359, 0.048, 0.0598, 0.075, 0.09, 0.105, 0.12, 0.135

But why these sizes in particular? Why not nice round numbers like 0.04 inches or at least useful fractions like 1/16 (0.0625)? These values aren't round numbers when converted to metric, either.

The answer lies in the gauge system of standard sheet metal thicknesses. In the US, standards for sheet metal come from the American Iron and Steel Institute (AISI). AISI standards tell manufacturers how thick to make steel sheets (the gauge) as well as what tolerances are allowed.

Many of our customers are used to the gauge system when ordering parts cut from steel sheet. So a customer might e-mail us to ask about getting a set of parts waterjet cut from 14 gauge steel, rather than asking for parts 0.075 inches thick.

Confusingly, as the gauge gets higher, the thickness gets lower. So 10 gauge steel is a stout 0.135 inches thick (about as thick as a stack of 2 quarters), whereas 24 gauge is a puny 0.0239 inches thick (thinner than a credit card).

In the chart below, you can see the thickness we sell, its corresponding gauge, and its metric equivalent. In the chart, inch and millimeter measurements are only for cold rolled steel sheet, not aluminum, not stainless steel, nor any other material. Other materials have their own gauge system. That's an article for another time.

Big Blue Saw's Nominal 
Thickness,
Inches
Gauge Minimum
Thickness,
Inches
Maximum
Thickness,
Inches
Nominal 
Thickness,
mm
Minimum
Thickness,
mm
Maximum
Thickness,
mm
 0.135 10 0.1285 0.1405 3.429 3.264 3.569
 0.12 11 0.1136 0.1256 3.048 2.885 3.190
 0.105 12 0.0986 0.1106 2.667 2.504 2.809
 0.09 13 0.0847 0.0947 2.286 2.151 2.405
 0.075 14 0.0697 0.0797 1.905 1.770 2.024
 0.0589 16 0.0548 0.0648 1.524 1.392 1.646
 0.048 18 0.0438 0.0518 1.219 1.113 1.316
 0.0359 20 0.0329 0.0389 0.912 0.836 0.988
 0.0299 22 0.0269 0.0329 0.759 0.683 0.836
 0.0239 24 0.0209 0.0269 0.607 0.531 0.683

 

For example, when Big Blue Saw gets an order for a part from 0.12 inch thick Cold Rolled Steel A366/1008, we'll use the gauge size sheet provided to us by our suppliers. Based on the standard tolerances,  the parts the customer receives may be as thin as 0.1136 inches or as thick as 0.1256 inches. Be sure to design your assemblies to tolerate this kind of variation in thickness.

If you're wondering how these sizes relate to various real world objects, read our article on deciding on a material thickness.

 

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Big Blue Saw
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Waterjet and Laser Cut Custom Parts.
Address for correspondence only:
3522 Ashford Dunwoody Rd NE #145
Atlanta, GA 30319
Phone: (678) WAY-SAW4 (678) 929-7294