16 gauge steel is 0.0598 in (1.52 mm) thick, 16 gauge galvanized is 0.0635 in (1.61 mm), 16 gauge stainless is sold at about 0.0595 in, and 16 gauge aluminum is 0.0508 in (1.29 mm).
Sheet metal gauge chart: steel, galvanized, stainless and aluminum thickness
Gauge 3 to 30
Gauge
Steel (in)
Steel (mm)
Steel (lb/ft²)
Galvanized (in)
Galvanized (mm)
Galvanized (lb/ft²)
Stainless (in)
Stainless (mm)
US Standard Gauge 1893 (in)
US Standard Gauge 1893 (mm)
Aluminum, B&S (in)
Aluminum, B&S (mm)
3
0.2391
6.074
10.000
–
–
–
–
–
0.2500
6.350
0.2294
5.827
4
0.2242
5.694
9.375
–
–
–
–
–
0.2344
5.953
0.2043
5.189
5
0.2092
5.314
8.750
–
–
–
–
–
0.2188
5.556
0.1819
4.620
6
0.1943
4.935
8.125
–
–
–
–
–
0.2031
5.159
0.1620
4.115
7
0.1793
4.555
7.500
–
–
–
–
–
0.1875
4.763
0.1443
3.665
8
0.1644
4.176
6.875
0.1681
4.271
7.031
0.1650
4.191
0.1719
4.366
0.1285
3.264
9
0.1495
3.796
6.250
0.1532
3.891
6.406
–
–
0.1563
3.969
0.1144
2.906
10
0.1345
3.416
5.625
0.1382
3.511
5.781
0.1350
3.429
0.1406
3.572
0.1019
2.588
11
0.1196
3.037
5.000
0.1233
3.132
5.156
0.1200
3.048
0.1250
3.175
0.0907
2.304
12
0.1046
2.657
4.375
0.1084
2.752
4.531
0.1054
2.677
0.1094
2.778
0.0808
2.052
13
0.0897
2.278
3.750
0.0934
2.373
3.906
0.0900
2.286
0.0938
2.381
0.0720
1.829
14
0.0747
1.898
3.125
0.0785
1.993
3.281
0.0751
1.908
0.0781
1.984
0.0641
1.628
15
0.0673
1.708
2.813
0.0710
1.803
2.969
–
–
0.0703
1.786
0.0571
1.450
16
0.0598
1.518
2.500
0.0635
1.613
2.656
0.0595
1.511
0.0625
1.588
0.0508
1.290
17
0.0538
1.367
2.250
0.0575
1.461
2.406
–
–
0.0563
1.429
0.0453
1.151
18
0.0478
1.215
2.000
0.0516
1.310
2.156
0.0480
1.219
0.0500
1.270
0.0403
1.024
19
0.0418
1.063
1.750
0.0456
1.158
1.906
0.0420
1.067
0.0438
1.111
0.0359
0.912
20
0.0359
0.911
1.500
0.0396
1.006
1.656
0.0355
0.902
0.0375
0.953
0.0320
0.813
21
0.0329
0.835
1.375
0.0366
0.930
1.531
–
–
0.0344
0.873
0.0285
0.724
22
0.0299
0.759
1.250
0.0336
0.854
1.406
0.0293
0.744
0.0313
0.794
0.0253
0.643
23
0.0269
0.683
1.125
0.0306
0.778
1.281
–
–
0.0281
0.714
0.0226
0.574
24
0.0239
0.607
1.000
0.0276
0.702
1.156
0.0235
0.597
0.0250
0.635
0.0201
0.511
25
0.0209
0.531
0.875
0.0247
0.626
1.031
–
–
0.0219
0.556
0.0179
0.455
26
0.0179
0.456
0.750
0.0217
0.550
0.906
0.0178
0.452
0.0188
0.476
0.0159
0.404
27
0.0164
0.418
0.688
0.0202
0.512
0.844
–
–
0.0172
0.437
0.0142
0.361
28
0.0149
0.380
0.625
0.0187
0.475
0.781
0.0151
0.384
0.0156
0.397
0.0126
0.320
29
0.0135
0.342
0.563
0.0172
0.437
0.719
–
–
0.0141
0.357
0.0113
0.287
30
0.0120
0.304
0.500
0.0157
0.399
0.656
–
–
0.0125
0.318
0.0100
0.254
Gauge numbers are not thicknesses. Steel gauges come from a weight per square foot (15 U.S.C. 206); the same gauge number means a different thickness in each metal. Order critical parts by decimal thickness.
Steel thickness = US Standard Gauge weight (lb per sq ft) / 41.82, rounded to 0.0001 in; Alro's Manufacturers' Standard Gauge chart pairs thickness and weight at that ratio. The lb per sq ft column is that defining weight; at the density NBS Letter Circular 24 gives for steel (0.2833 lb per cubic inch, 489.6 lb per cubic foot) a sheet of that thickness weighs about 2.4% less.
Galvanized gauge thickness includes the zinc: (US Standard Gauge weight + 2.5 oz per sq ft) / 41.82, per NBS Letter Circular 24. The galvanized weight column is that weight.
Stainless values are the nominal decimals a US service center (Alro) lists. Some supplier charts give stainless the 1893 US Standard Gauge fractions instead (16 gauge = 1/16 in = 0.0625 in); that set is in its own column. When it matters, order stainless by decimal thickness.
Aluminum, copper and brass sheet use the American Wire Gauge, also called Brown & Sharpe (NBS Letter Circular 24): the same numbers and diameters as AWG wire.
mm values are converted from the unrounded thickness, so a few differ by 0.001 to 0.002 mm from charts that convert the rounded inch figure.
Steel sheet gauges are defined by weight, not thickness. The 1893 act of Congress that set the US Standard Gauge for iron and steel sheet, still at 15 U.S.C. 206, lists a weight per square foot for each gauge and calls the thicknesses approximate: 16 gauge is 40 oz (2.5 lb) per square foot, 10 gauge is 90 oz (5.625 lb). NBS Letter Circular 24 explains that the thicknesses printed in the law assumed wrought iron at 480 lb per cubic foot. Galvanized sheet adds a zinc allowance to that weight, and nonferrous sheet uses a different gauge altogether. That is why 16 gauge means 0.0598 in in steel, 0.0635 in in galvanized and 0.0508 in in aluminum. Pick the column for the metal in hand, and order critical parts by decimal thickness.
Steel: Manufacturers' Standard Gauge
Uncoated carbon steel sheet is sold to the Manufacturers' Standard Gauge. Its thickness is the US Standard Gauge weight divided by 41.82 lb per square foot per inch of thickness; Alro's gauge chart pairs every gauge's decimal thickness and weight at that ratio (0.0598 in and 2.501 lb/ft² for 16 gauge):
thickness (in) = weight (lb/ft²) / 41.82
10 gauge: 5.625 / 41.82 = 0.1345 in. 16 gauge: 2.5 / 41.82 = 0.0598 in. The lb/ft² column in the chart is that defining weight. NBS Letter Circular 24 gives the density of steel as 0.2833 lb per cubic inch, which makes a 0.0598 in sheet about 2.44 lb/ft². A 4 x 8 ft sheet of 16 gauge is 80 lb by the gauge weight and about 78 lb at that density.
Galvanized
The Galvanized Sheet Gage adds 2.5 oz per square foot of zinc to the US Standard Gauge weight before converting, as NBS Letter Circular 24 describes. So galvanized gauges are thicker than bare steel of the same number: 16 gauge galvanized is (2.5 + 0.156) / 41.82 = 0.0635 in, against 0.0598 in bare, and weighs 2.656 lb/ft². Alro lists the same 0.0635 in for 16 gauge galvanized. The thickness includes the coating. If you measure a galvanized sheet with a micrometer, compare against the galvanized column, not the steel column.
Stainless steel
Suppliers publish two different sets of stainless gauge thicknesses:
Service-center nominal decimals. Alro lists 16 gauge stainless at 0.0595 in with a tolerance of plus or minus 0.003 in, 14 gauge at 0.0751 in and 11 gauge at 0.1200 in. Ryerson gives the same 0.0751 and 0.0595 figures. Online Metals rounds these to 0.075 and 0.060 in. This is the Stainless column.
The 1893 US Standard Gauge fractions. Some charts give stainless the thickness printed in the 1893 law: 16 gauge = 1/16 in = 0.0625 in, 14 gauge = 5/64 in = 0.0781 in. Metal Supermarkets lists these. They are in the US Standard Gauge column.
The two differ by 0.003 in at 16 gauge, as much as Alro's whole plus-or-minus tolerance. When a drawing calls for stainless by gauge alone, confirm the decimal thickness with the supplier before cutting.
Aluminum, copper and brass
NBS Letter Circular 24 describes the American Wire Gauge (Brown and Sharpe) as the gauge used in the US for nearly all nonferrous sheet, particularly copper, brass and aluminum, and lists each gauge's sheet thickness as the AWG wire diameter. 16 gauge aluminum is 0.0508 in, 18 gauge is 0.0403 in, 20 gauge is 0.0320 in. A 0.040 in aluminum sheet is close to 18 gauge, and 0.063 in is close to 14 gauge (0.0641 in). Online Metals advises buyers to use inch or metric thickness instead of gauge for exactly this reason: gauge is nonlinear and changes with the metal.
Measuring a sheet
Use a micrometer or a caliper on a clean edge, away from burrs, and read to 0.001 in.
Coatings add thickness; the galvanized gauge, for example, includes the zinc. Measure bare metal where you can, or allow for the coating.
Find the nearest value in the column for that metal. A reading of 0.050 in is 18 gauge (0.0478) on bare steel but 16 gauge (0.0508) on aluminum.
Sheet is rolled to a tolerance, so it rarely measures the exact table value. Alro lists plus or minus 0.003 in for 16 gauge stainless, and Online Metals notes that gauge thickness varies slightly by mill and batch. A difference of a few thousandths is within that; a full gauge step is not.
For pipe and tube walls, see the pipe schedule chart. Wire uses the same AWG numbers as aluminum sheet; the wire gauge chart lists every size to 40 AWG.