What Size Tube for Carports: Outside Size, Gauge and Wall Thickness
CarportBay Editorial Team Reviewed
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Six seller pages read on 2026-10-06 list a 14-gauge carport frame as 2.5x2.5 in tubing and a 12-gauge frame as a smaller 2.25x2.25 in tube. On the mild-steel gauge chart, 14-gauge is 0.0747 in thick and 12-gauge is 0.1046 in, 40.0 percent thicker. Kit listings show 2x2 in and 2x3 in tubing.
Seller pages read on 2026-10-06. Wall thickness from the Metal Supermarkets mild-steel chart.
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What size tube do carport sellers list?#
Carport frame tube is listed at 2.5x2.5 in for a 14-gauge frame and 2.25x2.25 in for a 12-gauge frame on six seller pages read on 2026-10-06. The 12-gauge tube is the smaller one on the outside, and its wall is the thicker one.
Outside size is the width of the tube across its face. Wall thickness is the steel between the outside face and the hollow center, and sellers state it as a gauge or in decimal inches.
| Seller (page date) | 14-gauge frame | 12-gauge frame |
|---|---|---|
| Midwest Steel Carports (2023-04-10) | 2.5x2.5 in, 0.0747 in | 2.25x2.25 in, 0.1046 in |
| America's Elite (undated) | 2.5x2.5 in | 2.25x2.25 in |
| Elite Metal Structures (2022-08-31) | 2.5x2.5 in | 2.25x2.25 in |
| WolfSteel (2026-07-24) | 2.5x2.5 in, 0.083 in | 2.25x2.25 in, 0.108 in |
| Alan's Factory Outlet help center (2023-10-01) | 2.5x2.5 in (standard) | 2.25x2.25 in (optional) |
| Coast to Coast Carports (2019-02-19) | 2.5x2.5 in, 0.068 to 0.074 in | 2.25x2.25 in, 0.095 to 0.1046 in |
Tube sizes are as each seller lists them on the date shown. Ask the seller for the frame's outside size and wall thickness in decimal inches before you order.
Keen's lists 2.5x2.5 in tubing in both 12-gauge and 14-gauge on a page read on 2026-10-05, so a quote can differ from the pairing in the table. Ask for the outside size of the frame tube you are quoted.
How thick is 12-gauge and 14-gauge tubing?#
A 14-gauge tube wall is 0.0747 in thick and a 12-gauge tube wall is 0.1046 in thick on the mild-steel gauge chart from Metal Supermarkets, which makes the 12-gauge wall 40.0 percent thicker.
What does gauge mean for tubing?
Gauge is a number that names the thickness of a sheet or tube wall, and a higher gauge number means a thinner wall. Gauge is a trade convention, so charts for mild steel and galvanized steel list different thicknesses for the same number. Frame gauge is the wall of the carport's tubing. Panel gauge is the thickness of the roof and wall sheets, so a 29-gauge panel and a 14-gauge frame are two different parts. For the full gauge and coating decoder, see the metal carport gauge and coating guide.
Is 12-gauge 30 or 40 percent thicker?
Twelve-gauge tubing is 40.0 percent thicker on the mild-steel chart (0.1046 against 0.0747 in), 38.1 percent thicker on the galvanized chart (0.1084 against 0.0785 in) and 30.1 percent thicker on the figures sellers print (0.108 against 0.083 in). The percent depends on the chart, so ask a seller for the wall in decimal inches.
| Basis | 14-gauge (in) | 12-gauge (in) | Ratio | Percent thicker |
|---|---|---|---|---|
| Mild steel (Metal Supermarkets) | 0.0747 | 0.1046 | 1.4003 | 40.0 |
| Galvanized steel (Metal Supermarkets) | 0.0785 | 0.1084 | 1.3809 | 38.1 |
| Sellers' own figures (WolfSteel, American Metal Garages, Direct Metal Structures) | 0.083 | 0.108 | 1.3012 | 30.1 |
| Midwest page prints "30% thicker" | 0.0747 | 0.1046 | 1.4003 | 40.0 (page says 30) |
| WolfSteel page prints "40% thicker" | 0.083 | 0.108 | 1.3012 | 30.1 (page says 40) |
Midwest Steel Carports prints "30% thicker" beside 0.0747 in and 0.1046 in, which compute to 40.0 percent. WolfSteel prints "40% thicker" beside 0.083 in and 0.108 in, which compute to 30.1 percent.
The chart in the diagram marks the mild-steel walls as bars on one scale, with the galvanized and seller figures set beside them.
How do the tube shapes compare by cross-section?#
A 12-gauge 2.25x2.25 in tube holds 23.9 percent more steel than a 14-gauge 2.5x2.5 in tube, and its second moment of area is 2.9 percent lower. Second moment of area is a measure of how a tube's cross-section resists bending.
Steel area equals the outside size squared minus the inside size squared, where the inside size is the outside size minus two walls. Second moment of area equals the outside size to the fourth power minus the inside size to the fourth power, divided by 12. Both use the listed outside size and the mild-steel wall, with square corners.
| Tube and gauge | Wall (in) | Steel area (sq in) | Second moment of area (in^4) | Against 14-gauge 2.5x2.5 in |
|---|---|---|---|---|
| 2x2 in, 14-gauge | 0.0747 | 0.5753 | 0.3559 | 20.6 percent less area, 49.9 percent lower |
| 2.25x2.25 in, 12-gauge | 0.1046 | 0.8976 | 0.6902 | 23.9 percent more area, 2.9 percent lower |
| 2.5x2.5 in, 14-gauge | 0.0747 | 0.7247 | 0.7111 | Reference |
| 2.5x2.5 in, 12-gauge | 0.1046 | 1.0022 | 0.9603 | 38.3 percent more area, 35.0 percent higher |
Arithmetic on the listed outside size and wall, with square corners, for the tube alone. A carport's ratings belong to the whole structure and the seller's design.
The diagram draws the 2x2 in, 2.25x2.25 in and 2.5x2.5 in tubes to the same scale, each labelled with its outside size and wall.
A 2.5x2.5 in tube at 14-gauge holds 26.0 percent more steel than a 2x2 in tube at 14-gauge and has 99.8 percent more second moment of area. Second moment of area rises with the fourth power of the outside size.
Which tube do sellers pair with which carport?#
Sellers pair the 12-gauge frame with heavier snow, larger buildings or specific regions, and each states its own condition on its own page. Midwest Steel Carports recommends 12-gauge at 35 psf snow load or higher, and psf means pounds per square foot.
| Seller (page date) | Condition for 12-gauge |
|---|---|
| Midwest Steel Carports (2023-04-10) | Recommends 12-gauge at 35 psf snow load or higher |
| Elite Metal Structures (2022-08-31) | For buildings taller than 10 feet or wider than 30 feet |
| Direct Metal Structures (2025-09-17) | Snow loads of 20 psf or more as the upgrade threshold |
| Coast to Coast Carports (2019-02-19) | Northern states, heavy snow, high wind and industrial use |
Wind, snow and drawing terms are as each seller lists them on the date shown. Local loads and your building department decide what a site requires.
Elite Metal Structures names buildings taller than 10 feet or wider than 30 feet. Direct Metal Structures lists snow loads of 20 psf or more as the upgrade threshold. Coast to Coast Carports names Northern states, heavy snow, high wind and industrial use.
Four sellers attach the 12-gauge option to snow load, building size or location, and none names a code edition. Alan's Factory Outlet lists 2.5x2.5 in tubing as its standard frame and 2.25x2.25 in tubing at 12-gauge as the optional choice.
What tube do carport kits use?#
Kit listings read on 2026-10-04 show 2x2 in tubing for a VersaTube 12x20 and 2 in tubing for an Arrow 12x20x9. A Mueller 20x20 listing says square tube without a size.
| Listing | Tube | Roof or panel gauge | Source and date |
|---|---|---|---|
| VersaTube 12x20 (Lowe's) | 2x2 in | 29-gauge panels | Listing read 2026-10-04 |
| Arrow 12x20x9 (ShedsDirect) | 2 in | 29-gauge roof | Listing read 2026-10-04 |
| Mueller 20x20 | Square tube, size unstated | 26-gauge PBR roof | Listing read 2026-10-04 |
| VersaTube frame-only listing | 2x3, 1.5x1.5 and 2x2 in at 14-gauge | Unlisted | Search listing read 2026-10-06 |
VersaTube's frame-only listing, read on 2026-10-06, shows 2x3, 1.5x1.5 and 2x2 in tubing at 14-gauge. Kit tube is smaller than the 2.5x2.5 in tube sellers list for installed frames.
The 29-gauge and 26-gauge figures on kit listings describe the roof or the panels. Frame gauge and panel gauge are two separate numbers, so read the frame line of a listing for the tube. Kit listings by size and seller are in the carport kit buying guide.
How strong is 2 inch square tubing?#
Strength of 2 inch square tubing depends on wall thickness, steel grade, length and load, and no figure for a carport follows from outside size alone.
By geometry, a 2x2 in tube at 14-gauge holds 0.5753 sq in of steel and has a second moment of area of 0.3559 in^4. A 2.5x2.5 in tube at the same gauge holds 0.7247 sq in and has 0.7111 in^4.
These figures describe the tube alone. A carport's wind and snow ratings belong to the whole structure, including its anchors, leg spacing, bracing and roof, and the seller's design sets them.
ASTM A500 is a standard specification for cold-formed carbon steel structural tubing in rounds and shapes, according to the Steel Tube Institute. A seller can name the standard and the steel grade of its tube, so ask for both when you compare quotes.
Does tube size change how much room you have?#
Leg tube size changes the clear width of a carport by twice the tube size, because a leg stands at each outer edge. On a 20 ft (240 in) carport with two Camrys, each 72.4 in wide, a 2 in tube leaves 236 in clear and a 3 in tube leaves 234 in.
| Leg tube at each outer edge | Clear width (in) | Door gap per space (in) | Change from 2.5 in tube |
|---|---|---|---|
| 2 in | 236 | 30.4 | +0.33 in |
| 2.25 in | 235.5 | 30.23 | +0.16 in |
| 2.5 in | 235 | 30.07 | +0.00 in |
| 3 in | 234 | 29.73 | -0.34 in |
Door gap is the clear width minus the two vehicle widths, divided by three, and it changes by 0.67 in between 2 in and 3 in tube. CarportBay's size pages use 2.5 in leg tubing.
The carport size guide and sizing calculator checks a footprint against your own vehicles. Footprints by width and length are listed on the carport sizes page. The 20x20 clear-width figures sit on the 20x20 carport dimensions page. The 30x40 figures sit on the 30x40 carport sizes page. Whole-structure measurements are in the carport dimensions guide.
What do legs, extensions and trusses use?#
Carport legs, leg extensions and trusses use the same family of steel tube as the frame. A leg is the vertical post at a corner or an outer edge. A leg extension is a tube section that adds height to a leg. A truss is the triangulated frame that carries the roof panels across the span. Sellers list the frame tube as 2.5x2.5 in at 14-gauge or 2.25x2.25 in at 12-gauge, so ask each seller which tube sits in each part.
What should a spec line state before you buy?#
A spec line for carport tubing states four fields: outside size, wall thickness in decimal inches, steel type and coating. An example reads: 2.5x2.5 in square tube, 14-gauge (0.0747 in, mild-steel chart), steel and coating as the seller states them.
The diagram sets the four fields in one line, so the same line can go to each seller. Wall thickness in decimal inches removes the chart question, because gauge numbers differ by chart.
Coating is the zinc or other layer on the steel. Galvanized steel is zinc-coated, and the galvanized chart lists 0.0785 in for 14-gauge and 0.1084 in for 12-gauge. Ask each seller for the same four fields, then compare the quotes line by line.
Where do wind, snow and permit questions go?#
Wind, snow and permit questions go to the seller for the structure's design rating and to your local building department for the rules at your address. Tube size and gauge are one part of a structure's rating, and loads depend on the site. Fees and thresholds by city are in the permit rules and thresholds.
Confirm current requirements with your local building department before beginning construction.
Frequently asked questions#
Six seller pages list a 14-gauge frame as 2.5x2.5 in tubing and a 12-gauge frame as 2.25x2.25 in tubing, read on 2026-10-06. Kit listings show 2x2 in and 2x3 in tubing. Sellers differ, so ask for the outside size and the wall thickness of the frame you are quoted.
Twelve-gauge tubing has the thicker wall: 0.1046 in against 0.0747 in on the mild-steel chart, 40.0 percent thicker. Six sellers pair the 12-gauge frame with a smaller 2.25x2.25 in tube. Gauge numbers differ by chart, so ask for the wall in decimal inches.
Gauge and tube size are two separate numbers. Tube size is the outside dimension, such as 2.5x2.5 in. Gauge names the wall thickness, so a 2.25x2.25 in tube at 12-gauge has a thicker wall than a 2.5x2.5 in tube at 14-gauge. Ask a seller for both numbers.
Strength depends on wall thickness, steel grade, length and load, and no figure for a carport follows from size alone. By geometry, a 2x2 in tube at 14-gauge holds 0.5753 sq in of steel, against 0.7247 sq in for 2.5x2.5 in at the same gauge.
Kit listings read on 2026-10-04 and 2026-10-06 show 2x2 in tubing for a VersaTube 12x20 and 2 in tubing for an Arrow 12x20x9. VersaTube's frame-only listing shows 2x3, 1.5x1.5 and 2x2 in tubing at 14-gauge. Kit tube is smaller than the 2.5x2.5 in tube sellers list for installed frames.
A seller's wind or snow rating belongs to the whole structure and is set by its design and the local load. Four sellers attach the 12-gauge upgrade to heavier snow or larger buildings in their own wording, and none names a code edition. Ask the seller what the rating covers.
Next steps#
Start with the number you are quoted. Ask each seller for the outside size of the frame tube and its wall thickness in decimal inches, then compare gauge only between the same steel chart. Match the 12-gauge option to the seller's own conditions, and confirm load and permit questions with your local building department before ordering. Then request quotes for the frame you chose. CarportBay carport size guide has the full range of sizes.
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