Standard Metal Gauges and Thickness
When using the following tables, remember that sheet metal gauge is legally defined by its weight per square foot - not by its thickness. The data in this first table is taken directly from the United States Code (USC Title 15, Chapter 6, Subchapter III, Section 206) which governs weights and measures with respect to trade in the US. All corresponding thicknesses are approximate (noted as such in the USC), and evidently rounded to the nearest simple fraction for ease of use - probably because in the time when this code was originally written (circa 1893), accurate measuring devices were not as common as they are today. These fractions are off a bit, (about 4.4% too thick) but may be "accurized" by making use of a correction factor of 0.956
These approximate thicknesses are based upon a 12"x12"x1" slab of steel weighing approximately 40.0 lbs (as implied by the entry for 24 gauge metal). The 0.956 correction factor is rooted in the idea that a slab of steel 12"x12"x1" actually weighs 41.84 lbs - meaning that a 12"x12" square of 24 gauge steel is, in reality, 1/41.84 inch thick ... not 1/40 inch, as might be inferred from the table, were it not understood that these are approximate thicknesses.
As mentioned before, a correction factor of 0.956 may be applied to
correct these numbers. For example, in the case of 24 gauge sheet metal,
the approximate thickness is listed as 1/40 or 0.025 inch. Using the
correction factor gives us (0.956 * 0.025in) = 0.0239in
... an accurate number. Corrected thicknesses can be found in the second table.
The numbers in this first table apply only to plain steel or iron. Galvanized steel, such as is found in garage door sections, will be somewhat thicker for a given gauge, as can be seen in the second table.
A color key has been provided that shows how the gauges are bracketed
into seven different groups. Within each group, adjacent gauges differ
by a fixed interval - measured in oz/ft^2. Gauges that
border two groups are shown in white.
| Color Key: | |||||||
|---|---|---|---|---|---|---|---|
| 20 oz | 10 oz | 5 oz | 4 oz | 2 oz | 1 oz | 1/2 oz | 1/4 oz |
| Thickness | Weight | |||||||
|---|---|---|---|---|---|---|---|---|
| Gauge# | Inch | Inch | mm | oz/ft^2 | lbs/ft^2 | kg/ft^2 | kg/m^2 | lbs/m^2 |
| 0000000 | 1/2 | .5 | 12.7 | 320 | 20.00 | 9.072 | 97.65 | 215.28 |
| 000000 | 15/32 | .46875 | 11.90625 | 300 | 18.75 | 8.505 | 91.55 | 201.82 |
| 00000 | 7/16 | .4375 | 11.1125 | 280 | 17.50 | 7.983 | 85.44 | 188.37 |
| 0000 | 13/32 | .40625 | 10.31875 | 260 | 16.25 | 7.371 | 79.33 | 174.91 |
| 000 | 3/8 | .375 | 9.525 | 240 | 15 | 6.804 | 73.24 | 161.46 |
| 00 | 11/32 | .34375 | 8.73125 | 220 | 13.75 | 6.237 | 67.13 | 148.00 |
| 0 | 5/16 | .3125 | 7.9375 | 200 | 12.50 | 5.67 | 61.03 | 134.55 |
| 1 | 9/32 | .28125 | 7.14375 | 180 | 11.25 | 5.103 | 54.93 | 121.09 |
| 2 | 17/64 | .265625 | 6.746875 | 170 | 10.625 | 4.819 | 51.88 | 114.37 |
| 3 | 1/4 | .25 | 6.35 | 160 | 10 | 4.536 | 48.82 | 107.64 |
| 4 | 15/64 | .234375 | 5.953125 | 150 | 9.375 | 4.252 | 45.77 | 100.91 |
| 5 | 7/32 | .21875 | 5.55625 | 140 | 8.75 | 3.969 | 42.72 | 94.18 |
| 6 | 13/64 | .203125 | 5.159375 | 130 | 8.125 | 3.685 | 39.67 | 87.45 |
| 7 | 3/16 | .1875 | 4.7625 | 120 | 7.5 | 3.402 | 36.62 | 80.72 |
| 8 | 11/64 | .171875 | 4.365625 | 110 | 6.875 | 3.118 | 33.57 | 74.00 |
| 9 | 5/32 | .15625 | 3.96875 | 100 | 6.25 | 2.835 | 30.52 | 67.27 |
| 10 | 9/64 | .140625 | 3.571875 | 90 | 5.625 | 2.552 | 27.46 | 60.55 |
| 11 | 1/8 | .125 | 3.175 | 80 | 5 | 2.268 | 24.41 | 53.82 |
| 12 | 7/64 | .109375 | 2.778125 | 70 | 4.375 | 1.984 | 21.36 | 47.09 |
| 13 | 3/32 | .09375 | 2.38125 | 60 | 3.75 | 1.701 | 18.31 | 40.36 |
| 14 | 5/64 | .078125 | 1.984375 | 50 | 3.125 | 1.417 | 15.26 | 33.64 |
| 15 | 9/128 | .0703125 | 1.7859375 | 45 | 2.8125 | 1.276 | 13.73 | 30.27 |
| 16 | 1/16 | .0625 | 1.5875 | 40 | 2.5 | 1.134 | 12.21 | 26.91 |
| 17 | 9/160 | .05625 | 1.42875 | 36 | 2.25 | 1.021 | 10.99 | 24.22 |
| 18 | 1/20 | .05 | 1.27 | 32 | 2 | .9072 | 9.765 | 21.53 |
| 19 | 7/160 | .04375 | 1.11125 | 28 | 1.75 | .7938 | 8.544 | 18.84 |
| 20 | 3/80 | .0375 | .9525 | 24 | 1.50 | .6804 | 7.324 | 16.15 |
| 21 | 11/320 | .034375 | .873125 | 22 | 1.375 | .6237 | 6.713 | 14.80 |
| 22 | 1/32 | .03125 | .793750 | 20 | 1.25 | .567 | 6.103 | 13.46 |
| 23 | 9/320 | .028125 | .714375 | 18 | 1.125 | .5103 | 5.493 | 12.11 |
| 24 | 1/40 | .025 | .635 | 16 | 1 | .4536 | 4.882 | 10.76 |
| 25 | 7/320 | .021875 | .555625 | 14 | .875 | .3969 | 4.272 | 9.42 |
| 26 | 3/160 | .01875 | .47625 | 12 | .75 | .3402 | 3.662 | 8.07 |
| 27 | 11/640 | .0171875 | .4365625 | 11 | .6875 | .3119 | 3.357 | 7.40 |
| 28 | 1/64 | .015625 | .396875 | 10 | .625 | .2835 | 3.052 | 6.73 |
| 29 | 9/640 | .0140625 | .3571875 | 9 | .5625 | .2551 | 2.746 | 6.05 |
| 30 | 1/80 | .0125 | .3175 | 8 | .5 | .2268 | 2.441 | 5.38 |
| 31 | 7/640 | .0109375 | .2778125 | 7 | .4375 | .1984 | 2.136 | 4.71 |
| 32 | 13/1280 | .01015625 | .25796875 | 61/2 | .40625 | .1843 | 1.983 | 4.37 |
| 33 | 3/320 | .009375 | .238125 | 6 | .375 | .1701 | 1.831 | 4.04 |
| 34 | 11/1280 | .00859375 | .21828125 | 51/2 | .34375 | .1559 | 1.678 | 3.70 |
| 35 | 5/640 | .0078125 | .1984375 | 5 | .3125 | .1417 | 1.526 | 3.36 |
| 36 | 9/1280 | .00703125 | .17859375 | 41/2 | .28125 | .1276 | 1.373 | 3.03 |
| 37 | 17/2560 | .006640625 | .168671875 | 41/4 | .265625 | .1205 | 1.297 | 2.87 |
| 38 | 1/160 | .00625 | .15875 | 4 | .25 | .1134 | 1.221 | 2.69 |
Metal Gauge Table - Including Galvanized Steel and Aluminum
| Gauge (ga) | Standard Steel Thickness (inches) | Galvanized Steel Thickness (inches) | Aluminum Thickness (inches) |
| 3 | 0.2391 | 0.2294 | |
| 4 | 0.2242 | 0.2043 | |
| 5 | 0.2092 | 0.1819 | |
| 6 | 0.1943 | 0.1620 | |
| 7 | 0.1793 | 0.1443 | |
| 8 | 0.1644 | 0.1285 | |
| 9 | 0.1495 | 0.1532 | 0.1144 |
| 10 | 0.1345 | 0.1382 | 0.1019 |
| 11 | 0.1196 | 0.1233 | 0.0907 |
| 12 | 0.1046 | 0.1084 | 0.0808 |
| 13 | 0.0897 | 0.0934 | 0.0720 |
| 14 | 0.0747 | 0.0785 | 0.0641 |
| 15 | 0.0673 | 0.0710 | 0.0571 |
| 16 | 0.0598 | 0.0635 | 0.0508 |
| 17 | 0.0538 | 0.0575 | 0.0453 |
| 18 | 0.0478 | 0.0516 | 0.0403 |
| 19 | 0.0418 | 0.0456 | 0.0359 |
| 20 | 0.0359 | 0.0396 | 0.0320 |
| 21 | 0.0329 | 0.0366 | 0.0285 |
| 22 | 0.0299 | 0.0336 | 0.0253 |
| 23 | 0.0269 | 0.0306 | 0.0226 |
| 24 | 0.0239 | 0.0276 | 0.0201 |
| 25 | 0.0209 | 0.0247 | 0.0179 |
| 26 | 0.0179 | 0.0217 | 0.0159 |
| 27 | 0.0164 | 0.0202 | 0.0142 |
| 28 | 0.0149 | 0.0187 | 0.0126 |
| 29 | 0.0135 | 0.0172 | 0.0113 |
| 30 | 0.0120 | 0.0157 | 0.0100 |
| 31 | 0.0105 | 0.0142 | 0.0089 |
| 32 | 0.0097 | 0.0134 | 0.0080 |
| 33 | 0.0090 | 0.0071 | |
| 34 | 0.0082 | 0.0063 | |
| 35 | 0.0075 | 0.0056 | |
| 36 | 0.0067 | ||
| 37 | 0.0064 | ||
| 38 | 0.0060 |
Aluminum thickness information derived from Engineers Edge and Online Conversion
