Sheet Metal Gauge Chart: Steel, Galvanized, Stainless and Aluminum
Every order we quote in our Portland shop starts with a gauge. Here is the chart we use, with thickness in inches and millimeters for the four metals contractors ask about most, and the gauges we actually run for flashing, coping and Z-furring.
Quick Answer
A higher gauge number means thinner metal, and the same gauge is a different thickness in different metals. 24 gauge steel is 0.0239" (0.61 mm). 24 gauge galvanized is 0.0276" (0.70 mm), because the zinc coat counts. 24 gauge aluminum is only 0.0201" (0.51 mm). Gauge is not a unit you can convert with a formula. You look it up in the table for that metal.
Sheet Metal Gauge Chart (16 to 28 Gauge)
| Gauge | Steel | Galvanized steel | Stainless steel | Aluminum |
|---|---|---|---|---|
| 16 ga | 0.0598" (1.52 mm) | 0.0635" (1.61 mm) | 0.0625" (1.59 mm) | 0.0508" (1.29 mm) |
| 18 ga | 0.0478" (1.21 mm) | 0.0516" (1.31 mm) | 0.0500" (1.27 mm) | 0.0403" (1.02 mm) |
| 20 ga | 0.0359" (0.91 mm) | 0.0396" (1.01 mm) | 0.0375" (0.95 mm) | 0.0320" (0.81 mm) |
| 22 ga | 0.0299" (0.76 mm) | 0.0336" (0.85 mm) | 0.0312" (0.79 mm) | 0.0253" (0.64 mm) |
| 24 ga | 0.0239" (0.61 mm) | 0.0276" (0.70 mm) | 0.0250" (0.64 mm) | 0.0201" (0.51 mm) |
| 26 ga | 0.0179" (0.45 mm) | 0.0217" (0.55 mm) | 0.0187" (0.47 mm) | 0.0159" (0.40 mm) |
| 28 ga | 0.0149" (0.38 mm) | 0.0187" (0.47 mm) | 0.0156" (0.40 mm) | 0.0126" (0.32 mm) |
Nominal thickness. Steel is Manufacturers' Standard Gauge, stainless is U.S. Standard Gauge, aluminum is Brown and Sharpe. Real sheet runs within a tolerance band, so when thickness is critical, spec the decimal, not just the gauge.
Why Galvanized Is Thicker Than Steel at the Same Gauge
Galvanized gauge numbers include the zinc coating. So 24 gauge galvanized measures about 0.004" more than 24 gauge bare steel. If you mic a galvanized sheet and compare it to a plain steel chart, it will look a gauge heavy. Use the galvanized column for galvanized material.
Aluminum and Copper Are Usually Ordered Differently
Aluminum has its own gauge table, but on the jobsite it is mostly called out in decimal inches: 0.032", 0.040", 0.050", 0.063". When we quote aluminum flashing, 0.040" is the usual call. Wider coping often goes heavier.
Copper is not ordered by gauge at all. It is sold by weight per square foot, and 16 oz and 20 oz are the two you see most for flashing and coping.
What Gauge for Flashing, Coping and Z-Furring?
- Flashing: 24 gauge G90 galvanized is the commercial standard. We bend prefinished or primed steel from 20 to 26 gauge, aluminum from 0.030" to 0.060", and 16 or 20 oz copper. See custom metal flashing.
- Parapet coping: G90 in 24, 22 or 20 gauge, or aluminum 0.040" to 0.080". Wider walls want the heavier end. See parapet coping and caps.
- Z-furring and hat channel: galvanized 16 to 26 gauge, with 1" to 4" depth. See Z-furring and hat channels.
A shop detail most charts won't tell you: in our shop, 16 and 18 gauge comes off coil, and 20 through 26 gauge is cut from sheet. That is why a Z in 16 or 18 gauge is a girt, and the same Z shape in 20 to 26 gauge is flashing. Different stock, different cut and bend time.
How to Call Out Gauge on an Order
Give us the metal, the gauge or decimal, and the finish: for example "24 ga G90 galvanized" or "0.040 aluminum, Kynar, color to match." If the spec gives a decimal, use the decimal. If you are not sure, tell us where the part goes and we will confirm the gauge before we cut. More in our guide to ordering custom sheet metal, or send it straight to the quote form for a 24-hour quote.
Sources
Frequently Asked Questions
How thick is 24 gauge steel?
24 gauge steel is 0.0239" (0.61 mm). 24 gauge galvanized is 0.0276" (0.70 mm), 24 gauge stainless is 0.0250" (0.64 mm), and 24 gauge aluminum is 0.0201" (0.51 mm).
Is 16 gauge thicker than 20 gauge?
Yes. The higher the gauge number, the thinner the metal. 16 gauge steel is 0.0598" and 20 gauge steel is 0.0359".
How thick is 22 gauge sheet metal?
22 gauge steel is 0.0299" (0.76 mm). Galvanized is 0.0336", stainless 0.0312", and aluminum 0.0253".
How many mm is 26 gauge?
26 gauge steel is 0.0179" or about 0.45 mm. 26 gauge galvanized is 0.0217" (0.55 mm).
What gauge is metal flashing?
24 gauge G90 galvanized is the common commercial call. Aluminum flashing is usually 0.040", and copper is usually 16 or 20 oz. The right choice depends on the detail and the spec.
Need Custom Sheet Metal Fabricated?
PDX Panels fabricates precision sheet metal for contractors across Portland, OR. Get a quote in 24 hours.