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Galvanized Steel Gauge Chart
2025-07-07
Gauge (Ga.) is a measurement unit of the thickness of a thin material (such as sheet metal or plastic film). We often use gauges with numbers to show the thickness or diameter of materials. But the non-ferrous metal and mild steel of the same Ga., their thicknesses are different. Besides, Steel Sheets and pipes of the same Ga. are also different.
Generally, for the same material, the higher the number, the thinner the metal sheet. For example, 16 gauge galvanized steel sheet thickness is 1.6129 mm (0.0635 inches); while 18 gauge galvanized steel sheet thickness is 1.3106 mm (0.0516 inches).
Galvanized Steel Gauge Chart
The steel sheet gauge table below is the equivalent sheet gauge thickness in inches or millimeters.
| Gauge (Ga.) | Mild steel (Inch) | Galvanized Steel (Inch) | Aluminum (Inch) | Mild steel (mm) | Galvanized Steel (mm) | Aluminum (mm) |
| 3 | 0.2391 | 0.2294 | 6.0731 | 5.8268 | ||
| 4 | 0.2242 | 0.2043 | 5.6947 | 5.1892 | ||
| 5 | 0.2092 | 0.1819 | 5.3137 | 4.6203 | ||
| 6 | 0.1943 | 0.162 | 4.9352 | 4.1148 | ||
| 7 | 0.1793 | 0.1443 | 4.5542 | 3.6652 | ||
| 8 | 0.1644 | 0.1681 | 0.1285 | 4.1758 | 4.27 | 3.2639 |
| 9 | 0.1495 | 0.1532 | 0.1144 | 3.7973 | 3.8913 | 2.9058 |
| 10 | 0.1345 | 0.1382 | 0.1019 | 3.4163 | 3.5103 | 2.5883 |
| 11 | 0.1196 | 0.1233 | 0.0907 | 3.0378 | 3.1318 | 2.3038 |
| 12 | 0.1046 | 0.1084 | 0.0808 | 2.6568 | 2.7534 | 2.0523 |
| 13 | 0.0897 | 0.0934 | 0.072 | 2.2784 | 2.3724 | 1.8288 |
| 14 | 0.0747 | 0.0785 | 0.0641 | 1.8974 | 1.9939 | 1.6281 |
| 15 | 0.0673 | 0.071 | 0.0571 | 1.7094 | 1.8034 | 1.4503 |
| 16 | 0.0598 | 0.0635 | 0.0508 | 1.5189 | 1.6129 | 1.2903 |
| 17 | 0.0538 | 0.0575 | 0.0453 | 1.3665 | 1.4605 | 1.1506 |
| 18 | 0.0478 | 0.0516 | 0.0403 | 1.2141 | 1.3106 | 1.0236 |
| 19 | 0.0418 | 0.0456 | 0.0359 | 1.0617 | 1.1582 | 0.9119 |
| 20 | 0.0359 | 0.0396 | 0.032 | 0.9119 | 1.0058 | 0.8128 |
| 21 | 0.0329 | 0.0366 | 0.0285 | 0.8357 | 0.9296 | 0.7239 |
| 22 | 0.0299 | 0.0336 | 0.0253 | 0.7392 | 0.8531 | 0.6426 |
| 23 | 0.0269 | 0.0306 | 0.0226 | 0.6833 | 0.7772 | 0.574 |
| 24 | 0.0239 | 0.0276 | 0.0201 | 0.6071 | 0.7004 | 0.5105 |
| 25 | 0.0209 | 0.0247 | 0.0179 | 0.5309 | 0.6274 | 0.4547 |
| 26 | 0.0179 | 0.0217 | 0.0159 | 0.4547 | 0.5512 | 0.4039 |
| 27 | 0.0164 | 0.0202 | 0.0142 | 0.4166 | 0.5131 | 0.3607 |
| 28 | 0.0149 | 0.0187 | 0.0126 | 0.3785 | 0.475 | 0.32 |
| 29 | 0.035 | 0.0172 | 0.0113 | 0.3429 | 0.4369 | 0.287 |
| 30 | 0.012 | 0.0157 | 0.01 | 0.3048 | 0.3988 | 0.254 |
| 31 | 0.0105 | 0.0142 | 0.0089 | 0.2667 | 0.3607 | 0.2261 |
| 32 | 0.0097 | 0.0134 | 0.008 | 0.2464 | 0.3404 | 0.2032 |
| 33 | 0.009 | 0.0071 | 0.2286 | 0.1803 | ||
| 34 | 0.0082 | 0.0063 | 0.2083 | 0.16 | ||
| 35 | 0.0075 | 0.0056 | 0.1905 | 0.1422 | ||
| 36 | 0.0067 | 0.1702 |
How to Calculate the Weight of Galvanized Sheet?
Let’s take 28 gauge galvanized sheet metal 4×8 for example. The weight of galvanized sheet is calculated by the formula:
W= Thickness (mm) * Width (m) * Length (m) * 7.85 (Density of steel = 7.85 kg/m3) + zinc layer weight
28 gauge is 0.475 mm, and the width and length are about 1.219 m and 2.438 m. Then the weight is about 11 kg (0.475*1.219*2.438*7.85).
Which Is Thicker, 20 Gauge or 22 Gauge Steel?
For the same material, 20 gauge is thicker than 22 gauge. 2o gauge galvanized sheet is 1.0058 mm (0.0396”) in thickness, while 22 gauge thickness is 0.8531 mm (0.0336”).
How About G90 Coating?
G90 indicates the zinc coating thickness of galvanized steel according to ASTM standards, such as G60, G140, etc. These numbers refer to the weight of zinc in Inch-Pound units of measurement. For example, G90 means the zinc coating of one square foot of sheet weighs 0.90 ounces.
1 oz/ft2 = 305.15 g/m2
So G90 (0.90 oz/ft2) = Z275 (275 g/m2)
Below is a table showing the commonly used codes for your reference.
| ASTM A653 | ISO Standard | Zinc Weight |
| G40 | Z120 | 120 g/m2 |
| G60 | Z180 | 180 g/m2 |
| G90 | Z275 | 275 g/m2 |
| G115 | Z350 | 350 g/m2 |
If you have any questions, please feel free to contact us!
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