Steel weight calculator

How to calculate the weight of steel

Weight per foot = section area in square inches x 3.403 lb

Steel weighs 0.2836 lb per cubic inch, the density Russel Metals sells its plate on. A one-foot length is 12 inches long, so each square inch of section weighs 0.2836 x 12 = 3.403 lb per foot. In metric units, steel weighs 7,850 kg per cubic metre, so each square millimetre of section weighs 0.00785 kg per metre.

The calculator works out the section area of the shape you choose. It then gives the weight per foot or metre, the weight of each piece and the weight of the whole quantity. At the same density, a cubic foot of steel weighs 490 lb.

Steel weight per foot for common bars and tubes

The table checks the calculator against the weights Russel Metals publishes for its cold finished rounds, squares, hexagons and flats. It also covers Russel's angle bar, mechanical tubing, HSS and pipe. The calculator uses carbon steel at 7,850 kg per cubic metre.

The round, square, hex and flat bars, the smaller angle, round tube and pipe agree within 0.1 percent. Square and rectangular HSS come out 2.8 to 4.5 percent heavy, because the calculator draws square corners and real HSS has rounded ones. For HSS, use the weight in your supplier's table. The larger angle comes out 1.4 percent light, because the calculator leaves out the fillet inside the corner.

Steel pipe weight

A pipe's nominal size is not its outside diameter: 2 in pipe measures 2.375 in across. To weigh pipe, choose Round tube or pipe, then enter the outside diameter and the wall for its size and schedule. The chart gives both for Schedule 40 and Schedule 80, with the weight per foot from Russel Metals' pipe schedule.

In these sizes, Russel's chart gives standard weight pipe the same wall as Schedule 40, and extra strong pipe the same wall as Schedule 80.

Worked examples

Pipe, inches. Take ten 20 ft lengths of 2 in Schedule 40 pipe, 2.375 in across with a 0.154 in wall. The section area is 1.0745 square inches, so a foot weighs 3.657 lb. Each length weighs 73.1 lb, and the ten weigh 731.4 lb. Russel Metals lists the same pipe at 3.653 lb per foot.

Pipe, millimetres. In millimetres, the same pipe measures 60.3 mm across with a 3.91 mm wall. Its section is 692.7 square millimetres, so a metre weighs 5.44 kg. Ten 6 m lengths weigh 326.2 kg.

Stainless bar. A 1 in round bar weighs 2.690 lb per foot in 304 stainless and 2.724 lb in 316. Russel Metals' stainless bar table lists 2.67 lb per foot for both, the same as its carbon steel weight.

With a price. At an example price of $1.00 per lb, the ten lengths of pipe cost $731.37 in material. The prices in these examples are round numbers for illustration, not market prices. Enter what you pay, per pound or per kilogram, and the calculator adds the material cost.

Carbon steel and stainless steel

The calculator uses 7,850 kg per cubic metre for carbon and structural steel, from Russel Metals' plate density. For stainless, it uses Outokumpu's 7.9 kg/dm³ for 304 and 8.0 kg/dm³ for 316. A part in 304 weighs 0.6 percent more than the same part in carbon steel, and a part in 316 weighs 1.9 percent more.

Published stainless weights differ. Russel Metals' stainless bar and stainless tubing tables list the same weight per foot as its carbon steel tables. Cleveland-Cliffs lists 8.03 g/cm³ for both 304 and 316, which is 1.6 percent above Outokumpu's value for 304.

Steel beams and channels

Beams and channels are not in this calculator, because you can read their weight from the name. The second number in a wide flange beam or channel name is its weight per foot. Metals Depot lists a W 8 x 31 beam at 31.00 lb per foot. It lists a C 3 x 4.1 channel at 4.10 lb per foot.

Russel Metals' wide flange beam table lists each beam by its metric and imperial names, such as W200 x 46 beside W8 x 31. With NIST's factor, 31 lb per foot converts to 46.1 kg per metre, the 46 in the metric name. Russel's standard channel table pairs C75 x 6 with C3 x 4.1 in the same way.

Theoretical weight and scale weight

The calculator gives the theoretical weight of the nominal size, and real stock varies within its standard. For ASTM A53 pipe, Russel Metals' pipe page lists a permitted variation of 5 percent over or under the weight per foot. It also lets the wall run up to 12.5 percent under its nominal thickness at any point.

Steel weight in a quote

On a quote for a fabricated part, the material line starts from the weight of each cut length. The guide to manufacturing quoting software explains where that material price comes from.