How thick is 16 gauge sheet metal?

16 gauge uncoated steel is 0.0598 inches (1.519 mm). Galvanised 16 gauge is slightly thicker at 0.0635 inches because of the zinc coating, stainless is 0.0625 inches, and 16 gauge aluminium is 0.0508 inches.

Does a higher gauge number mean thicker metal?

No. Higher gauge numbers are thinner material. 14 gauge steel is thicker than 20 gauge. The scale is inverted, the same as wire gauge.

Why does gauge thickness differ between metals?

Each metal uses its own gauge standard. Steel follows the Manufacturers' Standard Gauge, which is weight-based, while aluminium follows the Brown & Sharpe series. The same gauge number therefore gives different thicknesses.

What gauge is used for electrical enclosures?

General-purpose indoor enclosures are commonly 16 gauge steel; heavier industrial and outdoor enclosures use 14 or 12 gauge. Junction box covers and trim are often 18 or 20 gauge.

What gauge is 1/8 inch steel?

0.125 inches falls between 11 gauge (0.1196 in) and 10 gauge (0.1345 in). Shops normally call out 1/8 inch as plate and order it by decimal thickness rather than gauge, because neither gauge lands on 0.125 exactly.

How much does sheet steel weigh per square foot?

Multiply thickness in inches by 40.8 for uncoated steel, 41.6 for stainless and 14.0 for aluminium. 16 gauge steel at 0.0598 in works out to about 2.44 lb per square foot, so a 4 x 8 sheet is roughly 78 lb.

What is the minimum bend radius for a given gauge?

A safe starting point for mild steel is a bend radius equal to the material thickness, and 1.5 times thickness for 5052 aluminium. Thicker or harder material needs a larger radius or it cracks on the outside of the bend.

How do I convert sheet metal gauge to millimetres?

Look up the thickness in inches for the specific metal, then multiply by 25.4. This chart lists both columns so no conversion is needed.

Sheet Metal Gauge Chart

Gauge to thickness for the four metals tradespeople handle most, in inches with millimetres in brackets.

Quick answer

Higher gauge numbers are thinner metal. For uncoated steel: 10 ga = 0.1345 in, 12 ga = 0.1046 in, 14 ga = 0.0747 in, 16 ga = 0.0598 in, 18 ga = 0.0478 in, 20 ga = 0.0359 in. Aluminium at the same gauge number is thinner because it uses a different standard.

Gauge to thickness — inches (millimetres)

Steel follows the Manufacturers' Standard Gauge; galvanised adds the zinc coating; aluminium follows the Brown & Sharpe series.

Gauge	Steel	Galvanised steel	Stainless steel	Aluminium
3 ga	0.2391 (6.073)	—	—	0.2294 (5.827)
4 ga	0.2242 (5.695)	—	—	0.2043 (5.189)
5 ga	0.2092 (5.314)	—	—	0.1819 (4.620)
6 ga	0.1943 (4.935)	—	—	0.1620 (4.115)
7 ga	0.1793 (4.554)	—	0.1875 (4.762)	0.1443 (3.665)
8 ga	0.1644 (4.176)	0.1681 (4.270)	0.1719 (4.366)	0.1285 (3.264)
9 ga	0.1495 (3.797)	0.1532 (3.891)	0.1563 (3.970)	0.1144 (2.906)
10 ga	0.1345 (3.416)	0.1382 (3.510)	0.1406 (3.571)	0.1019 (2.588)
11 ga	0.1196 (3.038)	0.1233 (3.132)	0.1250 (3.175)	0.0907 (2.304)
12 ga	0.1046 (2.657)	0.1084 (2.753)	0.1094 (2.779)	0.0808 (2.052)
13 ga	0.0897 (2.278)	0.0934 (2.372)	0.0938 (2.383)	0.0720 (1.829)
14 ga	0.0747 (1.897)	0.0785 (1.994)	0.0781 (1.984)	0.0641 (1.628)
15 ga	0.0673 (1.709)	0.0710 (1.803)	0.0703 (1.786)	0.0571 (1.450)
16 ga	0.0598 (1.519)	0.0635 (1.613)	0.0625 (1.588)	0.0508 (1.290)
17 ga	0.0538 (1.367)	0.0575 (1.461)	0.0563 (1.430)	0.0453 (1.151)
18 ga	0.0478 (1.214)	0.0516 (1.311)	0.0500 (1.270)	0.0403 (1.024)
19 ga	0.0418 (1.062)	0.0456 (1.158)	0.0438 (1.113)	0.0359 (0.912)
20 ga	0.0359 (0.912)	0.0396 (1.006)	0.0375 (0.952)	0.0320 (0.813)
21 ga	0.0329 (0.836)	0.0366 (0.930)	0.0344 (0.874)	0.0285 (0.724)
22 ga	0.0299 (0.759)	0.0336 (0.853)	0.0313 (0.795)	0.0253 (0.643)
23 ga	0.0269 (0.683)	0.0306 (0.777)	0.0281 (0.714)	0.0226 (0.574)
24 ga	0.0239 (0.607)	0.0276 (0.701)	0.0250 (0.635)	0.0201 (0.511)
25 ga	0.0209 (0.531)	0.0247 (0.627)	0.0219 (0.556)	0.0179 (0.455)
26 ga	0.0179 (0.455)	0.0217 (0.551)	0.0188 (0.478)	0.0159 (0.404)
27 ga	0.0164 (0.417)	0.0202 (0.513)	0.0172 (0.437)	0.0142 (0.361)
28 ga	0.0149 (0.378)	0.0187 (0.475)	0.0156 (0.396)	0.0126 (0.320)
29 ga	0.0135 (0.343)	0.0172 (0.437)	0.0141 (0.358)	0.0113 (0.287)
30 ga	0.0120 (0.305)	0.0157 (0.399)	0.0125 (0.318)	0.0100 (0.254)

Published standard

Source & method: Millimetre values are exact conversions at 25.4 mm per inch. Mill tolerances of several thousandths are normal on any sheet product.

Common uses by gauge

Gauge	Steel thickness	Typical use
7 ga	0.1793 in (4.55 mm)	Structural plate, heavy brackets
10 ga	0.1345 in (3.42 mm)	Heavy machine guards, truck bodies
12 ga	0.1046 in (2.66 mm)	Industrial enclosures, shelving
14 ga	0.0747 in (1.90 mm)	Outdoor enclosures, strut and framing
16 ga	0.0598 in (1.52 mm)	General-purpose electrical enclosures
18 ga	0.0478 in (1.21 mm)	Ductwork, box covers, trim
20 ga	0.0359 in (0.91 mm)	Light ductwork, flashing
22 ga	0.0299 in (0.76 mm)	Register boots, light fabrication
24 ga	0.0239 in (0.61 mm)	Roof flashing, light ducting
26 ga	0.0179 in (0.46 mm)	Residential ductwork, light sheet

Weight per square foot

Shipping weight and structural load both scale directly with thickness. Steel 0.2836 lb/in3, stainless 0.2890, aluminium 0.0975.

Gauge	Steel lb/ft2	Stainless lb/ft2	Aluminium lb/ft2	Steel 4x8 sheet
4 ga	9.16	—	2.87	293 lb
6 ga	7.94	—	2.27	254 lb
8 ga	6.71	7.15	1.80	215 lb
10 ga	5.49	5.85	1.43	176 lb
12 ga	4.27	4.55	1.13	137 lb
14 ga	3.05	3.25	0.90	98 lb
16 ga	2.44	2.60	0.71	78 lb
18 ga	1.95	2.08	0.57	62 lb
20 ga	1.47	1.56	0.45	47 lb
22 ga	1.22	1.30	0.36	39 lb
24 ga	0.98	1.04	0.28	31 lb
26 ga	0.73	0.78	0.22	23 lb

Pounds per square foot = thickness in inches x 144 x density.

Source & method: Densities are published physical constants. A 4 x 8 sheet is 32 square feet, so sheet weight is simply the per-square-foot figure multiplied by 32.

Decimal thickness to nearest gauge

Working backwards from a caliper reading on uncoated steel.

Measured	Nearest steel gauge	Exact gauge thickness
0.2500 in	3 ga	0.2391 in
0.1875 in	6 ga	0.1943 in
0.1250 in	11 ga	0.1196 in
0.1000 in	12 ga	0.1046 in
0.0750 in	14 ga	0.0747 in
0.0625 in	16 ga	0.0598 in
0.0500 in	18 ga	0.0478 in
0.0400 in	19 ga	0.0418 in
0.0300 in	22 ga	0.0299 in
0.0250 in	24 ga	0.0239 in

Reading a gauge callout on a drawing

Gauge is a legacy weight standard, not a measurement. Steel gauge came from pounds per square foot, which is why 16 gauge steel and 16 gauge aluminium are not the same thickness and why no single conversion formula covers both. Order by decimal thickness whenever tolerance matters.

Galvanised material is always thicker than its uncoated equivalent by roughly 0.0035 inches, the zinc layer. That difference matters for punch clearance and for enclosure knockouts, so a die set up for 18 gauge uncoated will burr on 18 gauge galvanised.

For electrical work the practical range is 12 to 20 gauge steel: 12 and 14 for outdoor and industrial enclosures, 16 for general-purpose boxes and panels, 18 and 20 for covers, trim and duct. Anything lighter than 22 gauge will not hold a threaded knockout reliably.

Frequently asked

How thick is 16 gauge sheet metal?: 16 gauge uncoated steel is 0.0598 inches (1.519 mm). Galvanised 16 gauge is slightly thicker at 0.0635 inches because of the zinc coating, stainless is 0.0625 inches, and 16 gauge aluminium is 0.0508 inches.
Does a higher gauge number mean thicker metal?: No. Higher gauge numbers are thinner material. 14 gauge steel is thicker than 20 gauge. The scale is inverted, the same as wire gauge.
Why does gauge thickness differ between metals?: Each metal uses its own gauge standard. Steel follows the Manufacturers' Standard Gauge, which is weight-based, while aluminium follows the Brown & Sharpe series. The same gauge number therefore gives different thicknesses.
What gauge is used for electrical enclosures?: General-purpose indoor enclosures are commonly 16 gauge steel; heavier industrial and outdoor enclosures use 14 or 12 gauge. Junction box covers and trim are often 18 or 20 gauge.
What gauge is 1/8 inch steel?: 0.125 inches falls between 11 gauge (0.1196 in) and 10 gauge (0.1345 in). Shops normally call out 1/8 inch as plate and order it by decimal thickness rather than gauge, because neither gauge lands on 0.125 exactly.
How much does sheet steel weigh per square foot?: Multiply thickness in inches by 40.8 for uncoated steel, 41.6 for stainless and 14.0 for aluminium. 16 gauge steel at 0.0598 in works out to about 2.44 lb per square foot, so a 4 x 8 sheet is roughly 78 lb.
What is the minimum bend radius for a given gauge?: A safe starting point for mild steel is a bend radius equal to the material thickness, and 1.5 times thickness for 5052 aluminium. Thicker or harder material needs a larger radius or it cracks on the outside of the bend.
How do I convert sheet metal gauge to millimetres?: Look up the thickness in inches for the specific metal, then multiply by 25.4. This chart lists both columns so no conversion is needed.