How much does a steel bar weigh per metre?

Its cross-section in mm² times 7850 kg/m³, divided by a million. A 20 mm round bar: 314.16 mm² × 7850 / 1 000 000 = 2.47 kg/m. A 50 × 5 mm flat bar: 250 mm², 1.96 kg/m.

How do you calculate the weight of a square tube?

Section = side² − (side − 2 × wall)². A 40 × 40 × 3 mm steel tube: 444 mm², 3.49 kg/m with sharp corners. Rolled tubes have rounded corners, so the manufacturer's table gives a few per cent less; use that figure for anything ordered by weight.

How much does aluminium tube weigh?

Aluminium is about 2700 kg/m³, roughly a third of steel. A 40 × 40 × 2 mm aluminium square tube weighs 0.82 kg/m with sharp corners.

Metal · Weight

Metal weight calculator

Weight per metre = cross-section area × density. A 20 mm steel round bar is 314 mm² of section, so it weighs 2.47 kg/m; a 50 × 5 mm flat bar, 1.96 kg/m. Pick the material and the shape below for any size, in kg or lb, and the weight of the whole order.

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Weight per metre

— kg/m

One piece

— kg

Total

— kg

Section

— mm²

Cutting these from stock bars? The linear cutting optimizer works out how many bars your cut list needs, with the saw kerf, and which offcuts are worth keeping.

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Steel and aluminium weight charts

Worked out by the same code as the calculator above, from the nominal section with sharp corners: steel at 7850 kg/m³, aluminium at 2700 kg/m³.

Steel flat bar, kg/m

Width \ thickness, mm	3	4	5	6	8	10
20	0.47	0.63	0.79	0.94	1.26	1.57
25	0.59	0.79	0.98	1.18	1.57	1.96
30	0.71	0.94	1.18	1.41	1.88	2.36
40	0.94	1.26	1.57	1.88	2.51	3.14
50	1.18	1.57	1.96	2.36	3.14	3.93
60	1.41	1.88	2.36	2.83	3.77	4.71
80	1.88	2.51	3.14	3.77	5.02	6.28
100	2.36	3.14	3.93	4.71	6.28	7.85

Round bar, kg/m

Diameter, mm	6	8	10	12	16	20	25	30	40	50
Steel, kg/m	0.22	0.39	0.62	0.89	1.58	2.47	3.85	5.55	9.86	15.41
Aluminium, kg/m	0.08	0.14	0.21	0.31	0.54	0.85	1.33	1.91	3.39	5.30

Square tube

Square tube, mm	Steel, kg/m	Aluminium, kg/m	Area, mm²
20 × 20 × 2	1.13	0.39	144
25 × 25 × 2	1.44	0.50	184
30 × 30 × 2	1.76	0.60	224
30 × 30 × 3	2.54	0.87	324
40 × 40 × 2	2.39	0.82	304
40 × 40 × 3	3.49	1.20	444
40 × 40 × 4	4.52	1.56	576
50 × 50 × 3	4.43	1.52	564
50 × 50 × 4	5.78	1.99	736
60 × 60 × 3	5.37	1.85	684
60 × 60 × 4	7.03	2.42	896
80 × 80 × 4	9.55	3.28	1216
100 × 100 × 5	14.92	5.13	1900

Rolled tubes have rounded corners and weigh a few per cent less than these sharp-cornered figures, more so with thick walls. For anything ordered or designed by weight, use the manufacturer's table.

Steel equal angle

Equal angle, mm	Steel, kg/m	Area, mm²
20 × 20 × 3	0.87	111
25 × 25 × 3	1.11	141
30 × 30 × 3	1.34	171
40 × 40 × 4	2.39	304
50 × 50 × 5	3.73	475
60 × 60 × 6	5.37	684
80 × 80 × 8	9.55	1216
100 × 100 × 10	14.92	1900

Sheet and plate, kg/m²

Thickness, mm	0.5	0.8	1	1.5	2	3	4	5	6	8	10
Steel, kg/m²	3.93	6.28	7.85	11.78	15.70	23.55	31.40	39.25	47.10	62.80	78.50
Aluminium, kg/m²	1.35	2.16	2.70	4.05	5.40	8.10	10.80	13.50	16.20	21.60	27.00

How this is calculated

weight per metre (kg/m) = area (mm²) × density (kg/m³) / 1 000 000 round bar A = π d² / 4 flat bar A = b × t round tube A = π/4 × (D² − (D − 2t)²) square tube A = a² − (a − 2t)² angle A = t × (a + b − t) sheet kg/m² = t (mm) × density / 1000

Densities are typical values for each material; an alloy's data sheet beats all of them, and you can type your own. Every section is taken with sharp corners and constant wall thickness.

What this page does not do

No corner or root radii. Rolled tubes come out a few per cent lighter than this, hot-rolled angles a little heavier.
No tapered flanges. UPN, IPN and IPE sections are not here: use the manufacturer's table for those.
No strength. This is weight, not a structural check.