Determining Metal Gauges

Introduction to metal gauges

Sheet metal gauge is a measure of thickness where larger numbers = thinner metal.

  • But it's nonlinear
  • the scale is different for ferrous and non-ferrous metals
  • and there are different gauge standards (Brown & Sharpe, Birmingham, etc)

That being said. . .
These charts are a crucial tool for jewelers wanting to accurately convert from inches or millimeters to the equivalent gauge when purchasing and using round wire or flat sheet.

But I suggest that instead of using gauge, you follow the ASTM's suggestion and go with thickness measured in inches or millimeters instead:
"The use of gauge number is discouraged as being an archaic term of limited usefulness not having general agreement on meaning." (Specification ASTM A480-10a)

I highly recommend that you print a copy of this for your bench and your computer. This way you are always one glance away from knowing the gauge you want when you are hard at work on a piece of jewelry.

Brown and Sharpe Gauge to Inches to Millimeters Conversion Table

Brown and Sharpe Gauge to Inches to Millimeters Conversion Table
B & S GaugeInch (Decimal)Millimeter (mm)Inch (Fraction)
10.2897.348.
20.2586.543.
.0.2506.3501/4
.0.2345.95315/64
30.2295.827.
.0.2195.5567/32
40.2045.189.
.0.2035.15413/64
.0.1884.7623/16
50.1824.621.
.0.1724.36611/64
60.1624.115.
.0.1563.9695/32
70.1443.664.
.0.1413.5729/64
80.1283.263.
.0.1253.1751/8
90.1142.906.
.0.1092.7787/64
100.1022.588.
.0.0942.3813/32
110.0912.304.
120.0812.052.
.0.0781.9845/64
130.0721.828.
140.0641.628.
.0.0631.5881/16
150.0571.449.
160.0511.291.
.0.0471.1913/64
170.0451.149.
180.0401.024.
190.0360.912.
200.0320.812.
.0.0310.7951/32
210.0280.723.
220.0250.644.
230.0230.573.
240.0200.511.
250.0180.455.
260.0160.405.
.0.0160.3961/64
270.0140.360.
280.0130.321.
290.0110.286.
300.0100.255.
310.00890.226.
320.00800.200.
330.00710.180.
340.00630.160.
350.00560.142.
360.00500.130.
370.00450.114.
380.00400.100.

The American wire gauge (AWG) standards for wire

This table is for a single, solid, round wire.

AWG is also commonly used to specify body piercing jewelry sizes (especially smaller sizes), even when the material is not metallic.

Increasing gauge numbers denote decreasing wire diameters, which is similar to many other non-metric gauging systems such as SWG. This gauge system originated in the number of drawing operations used to produce a given gauge of wire. Very fine wire (for example, 30 gauge) required more passes through the drawing dies than 0 gauge wire did.

The American wire gauge (AWG) standards for wire
AWG #Diameter
(inch)
Diameter
(mm)
Area
(kcmil)
Area
(mm2)
0000 (4/0)0.460011.6840211.6000107.2193
000 (3/0)0.409610.4049167.806485.0288
00 (2/0)0.36489.2658133.076567.4309
0 (1/0)0.32498.2515105.534553.4751
10.28937.348183.692742.4077
20.25766.543766.371333.6308
30.22945.827352.634826.6705
40.20435.189441.741321.1506
50.18194.621333.102416.7732
60.16204.115426.251413.3018
70.14433.664920.818310.5488
80.12853.263616.50978.3656
90.11442.906413.09276.6342
100.10192.588210.38305.2612
110.09072.30488.23414.1723
120.08082.05256.52993.3088
130.07201.82785.17852.6240
140.06411.62774.10672.0809
150.05711.44953.25681.6502
160.05081.29082.58271.3087
170.04531.14952.04821.0378
180.04031.02371.62430.8230
190.03590.91161.28810.6527
200.03200.81181.02150.5176
210.02850.72290.81010.4105
220.02530.64380.64240.3255
230.02260.57330.50950.2582
240.02010.51060.40400.2047
250.01790.45470.32040.1624
260.01590.40490.25410.1288
270.01420.36060.20150.1021
280.01260.32110.15980.0810
290.01130.28590.12670.0642
300.01000.25460.10050.0509
310.00890.22680.07970.0404
320.00800.20190.06320.0320
330.00710.17980.05010.0254
340.00630.16010.03980.0201
350.00560.14260.03150.0160
360.00500.12700.02500.0127
370.00450.11310.01980.0100
380.00400.10070.01570.0080
390.00350.08970.01250.0063
400.00310.07990.00990.0050

Below is some information about Brown & Sharpe from Wikkipedia,

During the 19th and 20th centuries, Brown & Sharpe was one of the best-known and most influential machine tool builders and was a leading manufacturer of instruments for machinists (such as micrometers and indicators). Its reputation and influence were such that its name is often considered to be inseparably paired with certain industrial standards that it helped establish, including:

  • The American wire gauge (AWG) standards for wire;
  • The Brown & Sharpe taper in machine tool spindle tapers; and
  • The Brown & Sharpe worm threadform for worm gears.

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