Square Hollow Section (SHS) Properties

Mass, area, second moment and section modulus of 17 square hollow sections, including the corner radii.

Square hollow section (SHS) tube is the usual material for welded frames, machine bases and furniture. It has equal stiffness about both axes, easy flat faces for welding and bolting, and a clean look. The corners are rounded: the outside radius is 2 times the wall thickness for walls up to 6 mm, 2.5 times up to 10 mm and 3 times above, as in EN 10219.

The properties here are computed from the side, wall and corner radius, so they include the rounded corners.

The table

17 rows

Section (mm)	Side b (mm)	Wall t (mm)	Outside corner radius (mm)	Mass (kg/m)	Area (cm2)	I (cm4)	Elastic modulus W (cm3)	Radius of gyration i (cm)
20 x 20 x 2	20	2	4	1.05	1.34	0.7	0.7	0.72
25 x 25 x 2.5	25	2.5	5	1.64	2.09	1.7	1.4	0.9
30 x 30 x 3	30	3	6	2.36	3.01	3.5	2.3	1.08
40 x 40 x 3	40	3	6	3.3	4.21	9.3	4.7	1.49
40 x 40 x 4	40	4	8	4.2	5.35	11.1	5.5	1.44
50 x 50 x 3	50	3	6	4.25	5.41	19.5	7.8	1.9
50 x 50 x 4	50	4	8	5.45	6.95	23.7	9.5	1.85
60 x 60 x 4	60	4	8	6.71	8.55	43.6	14.5	2.26
70 x 70 x 5	70	5	10	9.7	12.36	84.6	24.2	2.62
80 x 80 x 4	80	4	8	9.22	11.75	111	27.8	3.07
80 x 80 x 5	80	5	10	11.27	14.36	131.4	32.9	3.03
100 x 100 x 5	100	5	10	14.41	18.36	271.1	54.2	3.84
100 x 100 x 6	100	6	12	16.98	21.63	311.5	62.3	3.79
120 x 120 x 6	120	6	12	20.75	26.43	562.2	93.7	4.61
120 x 120 x 8	120	8	20	26.41	33.64	676.9	112.8	4.49
150 x 150 x 8	150	8	20	33.95	43.24	1411.8	188.2	5.71
200 x 200 x 10	200	10	25	56.96	72.57	4251.1	425.1	7.65

Source and notes: Square hollow sections of common sizes (EN 10219, EN 10210). Corner radii follow EN 10219 (2t up to 6 mm wall, 2.5t up to 10 mm, 3t above); area, mass (7 850 kg/m3), I, W and i are computed from the dimensions including the corner radii. They agree with the makers' tables to within rounding (for example 100 x 100 x 5: 18.4 cm2, 14.4 kg/m).

How to use this table

Find the side and wall (for example 50 x 50 x 4).
Use W for bending stress (moment ÷ W) and I for deflection.
Use mass per meter for weight and cost; a tube is usually sold by the meter or by weight.

Worked example: an 80 × 80 × 4 tube carrying a 1 kN·m bending moment

From the table: area 11.75 cm², mass 9.22 kg/m, I = 111.0 cm⁴, W = 27.8 cm³.
Bending stress = M ÷ W = 1 × 10⁶ N·mm ÷ 27 800 mm³ = 36.0 MPa.
A 6 m length weighs 55.3 kg.

Notes and cautions

Rectangular hollow sections (RHS) have different values about the two axes; use the maker’s table for them.
Cold-formed tube has a slightly thicker corner and a different outside radius to hot-finished tube; the differences are small for design.
Mass is for steel at 7 850 kg/m³. The tolerance on wall thickness is about ±10 percent, so the real mass varies.

FAQ

What does 50 x 50 x 4 mean?

A square tube 50 mm on a side with a 4 mm wall.

Is square tube or round tube stronger?

For the same mass, square tube has the higher bending stiffness about its axes, while round tube is the better in torsion and for columns that can buckle in any direction. Square tube is easier to join.

Sources

EN 10219 (cold formed welded structural hollow sections) and EN 10210 (hot finished); the corner radius rule of EN 10219.
Properties computed from the dimensions; for example 100 x 100 x 5 comes out at 18.4 cm² and 14.4 kg/m, as in the makers’ tables.
Square hollow sections of common sizes (EN 10219, EN 10210). Corner radii follow EN 10219 (2t up to 6 mm wall, 2.5t up to 10 mm, 3t above); area, mass (7 850 kg/m3), I, W and i are computed from the dimensions including the corner radii. They agree with the makers' tables to within rounding (for example 100 x 100 x 5: 18.4 cm2, 14.4 kg/m).