What is Sheet Metal Gauge?
Sheet metal gauge refers to the thickness of sheet metal. Gauge is a unit of measurement for diameter that originated in North America as part of the Browne & Sharpe system.
The key things to know about sheet metal gauge are:
- The higher the gauge number, the thinner the sheet metal. Conversely, the lower the gauge number, the thicker the metal.
- For example, 8-gauge sheet metal is thicker than 16-gauge.
- Gauges measure sheet metal thickness in inches or millimeters, but are not tied to standard measurement systems.
- Different measurement systems are used for various metals, so the same gauge can correspond to different thicknesses depending on the metal.
- The standard range is from 30 gauge (thinnest) to 7 gauge (thickest).
When ordering custom metal parts, manufacturers will consult a steel gauge chart to determine the thickness. It’s important to verify the actual thickness with your supplier, especially for polished or treated materials.
You can refer to the sheet metal gauge table for the exact thickness of the sheet metal.
- Download Sheet Metal Gauge Chart (PDF File)
Sheet Metal Gauge Chart (inch, mm)
| GAUGE (Ga.) | Steel | Galvanized Steel | Stainless Steel | Aluminum | Electrical Steel |
|---|---|---|---|---|---|
| in (mm) | in (mm) | in (mm) | in (mm) | in (mm) | |
| 3 | 0.2391 (6.07) | – | – | – | – |
| 4 | 0.2242 (5.69) | – | – | – | – |
| 6 | 0.1943 (4.94) | – | – | 0.162 (4.1) | – |
| 7 | 0.1793 (4.55) | – | 0.1875 (4.76) | 0.1443 (3.67) | – |
| 8 | 0.1644 (4.18) | 0.1681 (4.27) | 0.1719 (4.37) | 0.1285 (3.26) | – |
| 9 | 0.1495 (3.80) | 0.1532 (3.89) | 0.1563 (3.97) | 0.1144 (2.91) | – |
| 10 | 0.1345 (3.42) | 0.1382 (3.51) | 0.1406 (3.57) | 0.1019 (2.59) | – |
| 11 | 0.1196 (3.04) | 0.1233 (3.13) | 0.1250 (3.18) | 0.0907 (2.30) | – |
| 12 | 0.1046 (2.66) | 0.1084 (2.75) | 0.1094 (2.78) | 0.0808 (2.05) | – |
| 13 | 0.0897 (2.28) | 0.0934 (2.37) | 0.094 (2.4) | 0.072 (1.8) | – |
| 14 | 0.0747 (1.90) | 0.0785 (1.99) | 0.0781 (1.98) | 0.0641 (1.63) | – |
| 15 | 0.0673 (1.71) | 0.0710 (1.80) | 0.07 (1.8) | 0.057 (1.4) | – |
| 16 | 0.0598 (1.52) | 0.0635 (1.61) | 0.0625 (1.59) | 0.0508 (1.29) | – |
| 17 | 0.0538 (1.37) | 0.0575 (1.46) | 0.056 (1.4) | 0.045 (1.1) | – |
| 18 | 0.0478 (1.21) | 0.0516 (1.31) | 0.0500 (1.27) | 0.0403 (1.02) | – |
| 19 | 0.0418 (1.06) | 0.0456 (1.16) | 0.044 (1.1) | 0.036 (0.91) | – |
| 20 | 0.0359 (0.91) | 0.0396 (1.01) | 0.0375 (0.95) | 0.0320 (0.81) | – |
| 21 | 0.0329 (0.84) | 0.0366 (0.93) | 0.034 (0.86) | 0.028 (0.71) | – |
| 22 | 0.0299 (0.76) | 0.0336 (0.85) | 0.031 (0.79) | 0.025 (0.64) | 0.0310 (0.787) |
| 23 | 0.0269 (0.68) | 0.0306 (0.78) | 0.028 (0.71) | 0.023 (0.58) | 0.0280 (0.711) |
| 24 | 0.0239 (0.61) | 0.0276 (0.70) | 0.025 (0.64) | 0.02 (0.51) | 0.0250 (0.64) |
| 25 | 0.0209 (0.53) | 0.0247 (0.63) | 0.022 (0.56) | 0.018 (0.46) | 0.0197 (0.50) |
| 26 | 0.0179 (0.45) | 0.0217 (0.55) | 0.019 (0.48) | 0.017 (0.43) | 0.0185 (0.47) |
| 27 | 0.0164 (0.42) | 0.0202 (0.51) | 0.017 (0.43) | 0.014 (0.36) | – |
| 28 | 0.0149 (0.38) | 0.0187 (0.47) | 0.016 (0.41) | 0.0126 (0.32) | – |
| 29 | 0.0135 (0.34) | 0.0172 (0.44) | 0.014 (0.36) | 0.0113 (0.29) | 0.0140 (0.35) |
| 30 | 0.0120 (0.30) | 0.0157 (0.40) | 0.013 (0.33) | 0.0100 (0.25) | 0.011 (0.27) |
| 31 | 0.0105 (0.27) | 0.0142 (0.36) | 0.011 (0.28) | 0.0089 (0.23) | 0.0100 (0.25) |
| 32 | 0.0097 (0.25) | – | – | – | – |
| 33 | 0.0090 (0.23) | – | – | – | 0.009 (0.23) |
| 34 | 0.0082 (0.21) | – | – | – | – |
| 35 | 0.0075 (0.19) | – | – | – | – |
| 36 | 0.0067 (0.17) | – | – | – | 0.007 (0.18) |
| 37 | 0.0064 (0.16) | – | – | – | – |
| 38 | 0.0060 (0.15) | – | – | – | 0.005 (0.127) |
Steel Gauge Chart (Manufacturers’ Standard)
Unit: inch, mmGauge No. Thickness
(in. )Thickness
( mm)7/0 0 — 6/0 0 — 5/0 0 — 4/0 0 — 3/0 0 — 2/0 0 — 1/0 0 — 1 — 2 — 3 0.2391 6.0731 4 0.2242 5.6947 5 0.2092 5.3137 6 0.1943 4.9352 7 0.1793 4.5542 8 0.1644 4.1758 9 0.1495 3.7973 10 0.1345 3.4163 11 0.1196 3.0378 12 0.1046 2.6568 13 0.0897 2.2784 14 0.0747 1.8974 15 0.0673 1.7094 16 0.0598 1.5189 17 0.0538 1.3665 18 0.0478 1.2141 19 0.0418 1.0617 20 0.0359 0.9119 21 0.0329 0.8357 22 0.0299 0.7595 23 0.0269 0.6833 24 0.0239 0.6071 25 0.0209 0.5309 26 0.0179 0.4547 27 0.0164 0.4166 28 0.0149 0.3785 29 0.0135 0.3429 30 0.012 0.3048 31 0.0105 0.2667 32 0.0097 0.2464 33 0.009 0.2286 34 0.0082 0.2083 35 0.0075 0.1905 36 0.0067 0.1702 37 0.0064 0.1626 38 0.006 0.1524 39 — 40 —
Galvanized Sheet Gauge Chart (inch, mm)
| Gauge No. | Thickness (in. mm) | ||
|---|---|---|---|
| 7/0 | (0000000) | — | |
| 6/0 | (000000) | — | |
| 5/0 | (00000) | — | |
| 4/0 | (0000) | — | |
| 3/0 | (000) | — | |
| 2/0 | (00) | — | |
| 1/0 | (0) | — | |
| 1 | — | ||
| 2 | — | ||
| 3 | — | ||
| 4 | — | ||
| 5 | — | ||
| 6 | — | ||
| 7 | — | ||
| 8 | 0.1681 | 4.2697 | |
| 9 | 0.1532 | 3.8913 | |
| 10 | 0.1382 | 3.5103 | |
| 11 | 0.1233 | 3.1318 | |
| 12 | 0.1084 | 2.7534 | |
| 13 | 0.0934 | 2.3724 | |
| 14 | 0.0785 | 1.9939 | |
| 15 | 0.071 | 1.8034 | |
| 16 | 0.0635 | 1.6129 | |
| 17 | 0.0575 | 1.4605 | |
| 18 | 0.0516 | 1.3106 | |
| 19 | 0.0456 | 1.1582 | |
| 20 | 0.0396 | 1.0058 | |
| 21 | 0.0366 | 0.9296 | |
| 22 | 0.0336 | 0.8534 | |
| 23 | 0.0306 | 0.7772 | |
| 24 | 0.0276 | 0.701 | |
| 25 | 0.0247 | 0.6274 | |
| 26 | 0.0217 | 0.5512 | |
| 27 | 0.0202 | 0.5131 | |
| 28 | 0.0187 | 0.475 | |
| 29 | 0.0172 | 0.4369 | |
| 30 | 0.0157 | 0.3988 | |
| 31 | 0.0142 | 0.3607 | |
| 32 | 0.0134 | 0.3404 | |
| 33 | — | ||
| 34 | — | ||
| 35 | — | ||
| 36 | — | ||
| 37 | — | ||
| 38 | — | ||
| 39 | — | ||
| 40 | — | ||
Stainless Steel Gauge Chart (U.S. Standard) (inch, mm)
| Gauge No. | Thickness (in. mm) | ||
|---|---|---|---|
| 7/0 | (0000000) | 0.5 | 12.7 |
| 6/0 | (000000) | 0.46875 | 11.90625 |
| 5/0 | (00000) | 0.43775 | 11.11885 |
| 4/0 | (0000) | 0.40625 | 10.31875 |
| 3/0 | (000) | 0.375 | 9.525 |
| 2/0 | (00) | 0.34375 | 8.73125 |
| 1/0 | (0) | 0.3125 | 7.9375 |
| 1 | 0.28125 | 7.14375 | |
| 2 | 0.26563 | 6.74688 | |
| 3 | 0.25 | 6.35 | |
| 4 | 0.23438 | 5.95313 | |
| 5 | 0.21875 | 5.55625 | |
| 6 | 0.20313 | 5.15938 | |
| 7 | 0.1875 | 4.7625 | |
| 8 | 0.17188 | 4.36563 | |
| 9 | 0.15625 | 3.96875 | |
| 10 | 0.14063 | 3.57188 | |
| 11 | 0.125 | 3.175 | |
| 12 | 0.10938 | 2.77813 | |
| 13 | 0.09375 | 2.38125 | |
| 14 | 0.07813 | 1.98438 | |
| 15 | 0.07031 | 1.78594 | |
| 16 | 0.0625 | 1.5875 | |
| 17 | 0.05625 | 1.42875 | |
| 18 | 0.05 | 1.27 | |
| 19 | 0.04375 | 1.11125 | |
| 20 | 0.0375 | 0.9525 | |
| 21 | 0.03438 | 0.87313 | |
| 22 | 0.03125 | 0.79375 | |
| 23 | 0.02813 | 0.71438 | |
| 24 | 0.025 | 0.635 | |
| 25 | 0.02188 | 0.55563 | |
| 26 | 0.01875 | 0.47625 | |
| 27 | 0.01719 | 0.43656 | |
| 28 | 0.01563 | 0.39688 | |
| 29 | 0.01406 | 0.35719 | |
| 30 | 0.0125 | 0.3175 | |
| 31 | 0.01094 | 0.27781 | |
| 32 | 0.01016 | 0.25797 | |
| 33 | 0.00938 | 0.23813 | |
| 34 | 0.00859 | 0.21828 | |
| 35 | 0.00781 | 0.19844 | |
| 36 | 0.00703 | 0.17859 | |
| 37 | 0.00664 | 0.16867 | |
| 38 | 0.00625 | 0.15875 | |
| 39 | — | ||
| 40 | — | ||
Aluminum Gauge Chart (inch, mm)
| Gauge No. | Thickness (in. mm) | ||
|---|---|---|---|
| 7/0 | (0000000) | 0.65135 | 16.54439 |
| 6/0 | (000000) | 0.58005 | 14.73324 |
| 5/0 | (00000) | 0.51655 | 13.12034 |
| 4/0 | (0000) | 0.46 | 11.684 |
| 3/0 | (000) | 0.40964 | 10.40486 |
| 2/0 | (00) | 0.3648 | 9.26592 |
| 1/0 | (0) | 0.32486 | 8.25144 |
| 1 | 0.2893 | 7.34822 | |
| 2 | 0.25763 | 6.5438 | |
| 3 | 0.22942 | 5.82727 | |
| 4 | 0.20431 | 5.18947 | |
| 5 | 0.18194 | 4.62128 | |
| 6 | 0.16202 | 4.11531 | |
| 7 | 0.14428 | 3.66471 | |
| 8 | 0.12849 | 3.26365 | |
| 9 | 0.11443 | 2.90652 | |
| 10 | 0.10189 | 2.58801 | |
| 11 | 0.09074 | 2.30485 | |
| 12 | 0.08081 | 2.05252 | |
| 13 | 0.07196 | 1.82781 | |
| 14 | 0.06408 | 1.62773 | |
| 15 | 0.05707 | 1.44953 | |
| 16 | 0.05082 | 1.29083 | |
| 17 | 0.04526 | 1.14953 | |
| 18 | 0.0403 | 1.0237 | |
| 19 | 0.03589 | 0.91161 | |
| 20 | 0.03196 | 0.81181 | |
| 21 | 0.02846 | 0.72293 | |
| 22 | 0.02535 | 0.64381 | |
| 23 | 0.02257 | 0.5733 | |
| 24 | 0.0201 | 0.51054 | |
| 25 | 0.0179 | 0.45466 | |
| 26 | 0.01594 | 0.40488 | |
| 27 | 0.0142 | 0.36055 | |
| 28 | 0.01264 | 0.32108 | |
| 29 | 0.01126 | 0.28593 | |
| 30 | 0.01003 | 0.25464 | |
| 31 | 0.00893 | 0.22677 | |
| 32 | 0.00795 | 0.20193 | |
| 33 | 0.00708 | 0.17983 | |
| 34 | 0.0063 | 0.16012 | |
| 35 | 0.00561 | 0.1426 | |
| 36 | 0.005 | 0.127 | |
| 37 | 0.00445 | 0.11311 | |
| 38 | 0.00397 | 0.10071 | |
| 39 | 0.00353 | 0.08969 | |
| 40 | 0.00314 | 0.07986 | |
Brass Gauge Chart (Brown & Sharpe) (inch, mm)
| Gauge No. | Thickness (in. mm) | ||
|---|---|---|---|
| 7/0 | (0000000) | 0.65135 | 16.54439 |
| 6/0 | (000000) | 0.58005 | 14.73324 |
| 5/0 | (00000) | 0.51655 | 13.12034 |
| 4/0 | (0000) | 0.46 | 11.684 |
| 3/0 | (000) | 0.40964 | 10.40486 |
| 2/0 | (00) | 0.3648 | 9.26592 |
| 1/0 | (0) | 0.32486 | 8.25144 |
| 1 | 0.2893 | 7.34822 | |
| 2 | 0.25763 | 6.5438 | |
| 3 | 0.22942 | 5.82727 | |
| 4 | 0.20431 | 5.18947 | |
| 5 | 0.18194 | 4.62128 | |
| 6 | 0.16202 | 4.11531 | |
| 7 | 0.14428 | 3.66471 | |
| 8 | 0.12849 | 3.26365 | |
| 9 | 0.11443 | 2.90652 | |
| 10 | 0.10189 | 2.58801 | |
| 11 | 0.09074 | 2.30485 | |
| 12 | 0.08081 | 2.05252 | |
| 13 | 0.07196 | 1.82781 | |
| 14 | 0.06408 | 1.62773 | |
| 15 | 0.05707 | 1.44953 | |
| 16 | 0.05082 | 1.29083 | |
| 17 | 0.04526 | 1.14953 | |
| 18 | 0.0403 | 1.0237 | |
| 19 | 0.03589 | 0.91161 | |
| 20 | 0.03196 | 0.81181 | |
| 21 | 0.02846 | 0.72293 | |
| 22 | 0.02535 | 0.64381 | |
| 23 | 0.02257 | 0.5733 | |
| 24 | 0.0201 | 0.51054 | |
| 25 | 0.0179 | 0.45466 | |
| 26 | 0.01594 | 0.40488 | |
| 27 | 0.0142 | 0.36055 | |
| 28 | 0.01264 | 0.32108 | |
| 29 | 0.01126 | 0.28593 | |
| 30 | 0.01003 | 0.25464 | |
| 31 | 0.00893 | 0.22677 | |
| 32 | 0.00795 | 0.20193 | |
| 33 | 0.00708 | 0.17983 | |
| 34 | 0.0063 | 0.16012 | |
| 35 | 0.00561 | 0.1426 | |
| 36 | 0.005 | 0.127 | |
| 37 | 0.00445 | 0.11311 | |
| 38 | 0.00397 | 0.10071 | |
| 39 | 0.00353 | 0.08969 | |
| 40 | 0.00314 | 0.07986 | |
How to Read a Sheet Metal Gauge Chart
A sheet metal gauge chart shows the gauge number and its corresponding thickness in inches and millimeters for different metals. For instance:
- 16 gauge steel = 0.0598 in (1.5189 mm)
- 16 gauge galvanized steel = 0.0635 in (1.6129 mm)
The same gauge number can refer to different thicknesses for various metals due to their unique properties and characteristics that affect how they are drawn or formed to size. Always check the metal type when determining the right gauge for your application.
History of Sheet Metal Gauge
The use of “GAUGE” as a measure of thickness dates back to the early days of the American Industrial Revolution.
Wire makers sought a way to quantify their products and the gravimetric method was the simplest solution.
However, this method created difficulties when buyers ordered a specific amount of wire without specifying the diameter.
To address this issue, wire craftsmen started to report the diameter based on the number of times the wire was drawn. This is the origin of the GAUGE measurement system.
Because each drawing reduced the diameter of the wire, the more times it was drawn, the smaller the diameter of the wire. As a result, the larger the GAUGE number, the smaller the diameter of the corresponding wire.
Steel mills eventually adopted a similar approach when rolling plates as it was easier to weigh than to measure the thickness.
Steel plates could be sold based on the unit area weight, with the thinner plates weighing less per square foot.
Steel mills found it convenient to specify the thickness of their steel plates using the GAUGE number system, which was based on the GAUGE number system used by the wire industry.
The origins of the GAUGE number system were influenced by the level of industrial development at the time.
In the 18th and 19th centuries, industrial standards in the United States were largely nonexistent, so each manufacturer had to develop its own standards.
Over time, these standards became more consistent, and the unified standard wire gauge (SWG), steel sheet material manufacturer’s standard gauge (MSG), and non-ferrous metals’ American Wire Gauge (AWG) were established.
Related reading: Ferrous vs Non-ferrous Metals
Wire craftsmen aimed to reduce the cross-section of the wire as quickly as possible, but due to the limitations of material deformation, the amount of diameter reduction in a single pass was limited.
Over time, the wire industry determined the optimal number of times required for wire drawing, resulting in the exponential decay curve seen in GAUGE numbers.
It is important to note that the same GAUGE number may correspond to different thickness values for different metals.
For example, 21 gauge corresponds to a standard steel thickness of 0.0329 inches (0.84mm), while it corresponds to a galvanized steel thickness of 0.0366 inches (0.93mm) and an aluminum thickness of 0.028 inches (0.71mm).
It is important to verify the actual thickness with your supplier, especially if you are receiving polished or treated materials.
The same gauge value will correspond to different thickness values for different metals. This is because the properties and characteristics of different metals affect their ability to be drawn or formed into a specific gauge size.
For example, 21 gauge corresponds to a thickness of 0.0329 inches (0.84mm) for standard steel, 0.0366 inches (0.93mm) for galvanized steel, and 0.028 inches (0.71mm) for aluminum.
It is important to consider the type of metal being used when determining the appropriate gauge for a specific application, as this will affect the final thickness and weight per unit area of the material.
