Steel rectangular tube weight calculator
Rectangular HSS, the other half of the hollow structural section family. Trailer frames, equipment guards, gate posts. 3" × 2" × 1/4" wall is 7.11 lb/ft. 4" × 2" × 1/4" is 8.81 lb/ft. Enter the outside dimensions and wall, get the weight.
Updated September 2026
Quick answer
Calculate rectangular HSS weight by width, height, and wall thickness.
Rectangular HSS weight per foot
Formula: 2t(W + H − 2t) − (4 − π)(Ro² − Ri²), times 12 × 0.2836 lb/in³. The second term takes out the rounded corners: A500 tube has an outside corner radius Ro of about twice the wall and an inside radius Ri of one wall. That is how AISC figures its published HSS weights, and it is why 3×2×1/4 comes out 7.11 and 6×4×1/4 comes out 15.62, the same as the AISC tables. A square-corner formula runs heavy by up to about 8% on these sizes, worst on thick walls.
Questions welders ask about this one
What is the difference between rectangular and square tube?
Just the shape. Square tube has equal sides, rectangular tube has different width and height. Both are HSS (Hollow Structural Section) per ASTM A500. The weight formula is the same: outer area minus inner area, less the rounded corners, times length times density. Rectangular tube is the better choice when you need stiffness in one direction more than the other.
What size rectangular tube for a trailer frame?
Most utility trailer frames use 3" × 2" or 4" × 2" rectangular tube with 3/16" or 1/4" wall. A 16-foot trailer main rail in 4" × 2" × 1/4" weighs about 141 lb per rail (8.81 lb/ft × 16 ft). Cross members are typically lighter: 2" × 1" or 3" × 1-1/2" at 0.120" wall.
Is rectangular HSS the same grade as square HSS?
Yes. Both are made to ASTM A500. Grade B (46 ksi yield) is the most common. Grade C (50 ksi yield) is specified when higher strength is needed. The density and weight per foot are identical across grades. The only difference is mechanical properties.
Weight is only half of material cost. To turn these pounds into a number you can quote, run the weld cost calculator for wire, gas, and labor per inch, or the job pricing calculator to build the whole bid.
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