1 x 1 Square Tubing Dimensions | Sizes, Weights, and Specs

1 x 1 square tubing means a square hollow steel tube with a 1.000-inch outside width and height, with wall thickness set by the gauge or decimal.

For the full breakdown, see our best 1 x 1 Square Tubing guide.

Buyers often confuse whether “1 x 1” is the inside or outside measurement. Suppliers measure square tube by its outer dimensions and wall thickness, not the opening’s size. So, 1 x 1 square tubing has 1-inch outside width and height, and the inside opening is smaller once walls are subtracted. Two pieces can look identical yet carry different loads, weigh differently, and weld differently based on wall thickness. This guide breaks down standard sizes, gauges, weights, and steel types so you order correctly.

What “1 x 1” Means

Supplier catalogs define 1 x 1 square tubing by outside width, height, and wall thickness. All Metals Inc. lists 1 x 1 x 14 gauge Grade A500 with a 1.000-inch outside width and height. If you need a tube to slide over another 1-inch piece or insert something through, measure the inside opening—it is always smaller than 1 inch.

Standard Wall Gauges and Weight Per Foot

Wall thickness ranges from light 18-gauge to heavy 0.188-inch, changing weight per foot. McNeilus Steel’s chart lists these common figures used nationwide:

Heavier walls add strength and stiffness but cost and weigh more. For light furniture frames, 16 or 14 gauge is typical; for structural frames and trailers, 11 gauge or heavier is common.

Steel Types: A500, A513, and 4130

• A500 structural tubing is standard for building frames, available in 1 x 1 sizes across gauges including 11 gauge, meeting structural specs.
• A513 mechanical/ERW tubing offers tighter tolerances for manufacturing and fabrication where consistency matters more than certification.
• 4130 chromoly airframe tubing is the aircraft-grade option in 1 x 1 sizes with 0.035, 0.049, and 0.065-inch walls. Stronger per pound than mild steel, it requires different welding techniques.
• Aluminum square tubing at the same 1 x 1 dimension weighs one-third of steel but has different strength limits, not a drop-in replacement for load-bearing steel.

These materials are not interchangeable. Substituting A513 or 4130 for A500 without re-engineering is a safety risk. Never assume equal capacity just because outside dimensions match.

How to Specify and Order

Provide outside width, height, wall thickness, material grade, and length. Example: A500B square tube, 1 inch x 1 inch x 0.083-inch wall, 10-foot length. Engineers use decimal inches; hobbyists use gauges—14 ga is 0.083 inch, 16 ga is 0.065 inch. Measure outside faces with calipers and check wall at the cut end; inside opening alone isn’t enough.

Pricing varies: a 2-foot 14 gauge tube might run ~$4.32, while a 10-foot 11 gauge stick runs ~$22.46, but check current supplier rates.