How to calculate steel weight and cost per foot in dollars

The one formula behind every steel weight

Every weight in this guide comes from one fact. A cubic foot of steel weighs 490 pounds, which is the same as 7850 kg per cubic metre. The weight of any piece is its volume times that number.

Steel sections are measured in inches, so work in square inches and get pounds per foot directly. One square inch of area, one foot long, weighs 490 ÷ 144 = 3.403 lb.

Check it against a real shape. The W12x26 has a listed area of 7.65 in² in the AISC Shapes Database. Multiply 7.65 by 3.403 and you get 26.03 lb/ft, which matches the 26 in the name.

Hand formulas for flats, bars, plates and pipe

Plain shapes have no tapers or radii, so you can calculate them yourself. Put every dimension in inches and the formulas give pounds per foot (pounds per square foot for plate).

The tube formula ignores the rounded outside corners and uses the nominal wall, so it reads a little high. A 4x4x1/4 HSS is listed at 12.21 lb/ft in the AISC database, against 12.8 lb/ft from the formula. For an order, use the supplier's table.

For a plate, multiply the pounds per square foot by the area. A 1/2 in plate that is 4 ft by 8 ft has an area of 32 ft², so it weighs 20.4 × 32 = 653 lb.

Weight calculator

This uses the same formulas as the table above. Change the numbers and the weight and cost update. Everything runs on your device.

Rebar weight chart

Reinforcing bar is one of the most searched steel weights. US bar sizes are numbered in eighths of an inch, so a #8 bar has a nominal diameter of 8/8 = 1 inch. The weight is the nominal diameter squared times 2.673. Stock bars are commonly 20 ft long, so the last two columns give the weight of one bar and the number of bars in a ton of 2,000 lb.

These are nominal weights from the ASTM A615 bar sizes. Mill bars can differ slightly. If you buy by weight, the scale ticket will be a little off the chart, so allow for that in the quote.

W-shapes, channels and angles: read the table

Do not draw a W-beam and calculate it. Rolled shapes have tapered or filleted flange and web junctions that a simple drawing misses. The AISC Shapes Database lists the weight per foot for every shape, and for a W-shape it is also the second number in the name: W12x26 is 26 lb/ft, W18x35 is 35 lb/ft.

The cost per foot is then one multiplication:

For channels, angles and tees the weight per foot is also in the name: C9x15 is 15 lb/ft and WT6x13 is 13 lb/ft. Angles are the exception, because the name gives the leg sizes and thickness, such as L4x4x1/2. That angle weighs 12.8 lb/ft, and you read it from the table.

Worked example: weight and cost of a small job

Here is a short material list priced at $0.55 per pound. The price is an example, so use your supplier's. Weight for each line is pounds per foot times length times quantity.

Quotes are often given per hundredweight (cwt, 100 lb) or per ton. Divide by 100 or by 2,000 to get the price per pound, so $55 per cwt and $1,100 per ton are both $0.55 per lb. The guide to steel price conversions covers this in detail. One price for every line is a simplification, because beams, flats and rebar are usually priced differently, so use a separate price for each category.

What an estimate usually leaves out

Weight times price is the price of steel and nothing else. Keep these as separate lines so the steel number stays clean:

• Cutting waste, since you buy stock lengths and cut them down.
• Fabrication and labor, welding material and bolts.
• Shop primer, paint or galvanizing.
• Freight and handling to the site.
• Sales tax and any surcharges.
• A change in the steel price between the day you quote and the day you buy.

Mistakes that change the number

• Inches and feet mixed up. The formulas above want inches for the section and feet for the length. A 20 ft bar entered as 20 in is off by a factor of 12.
• Ton read three ways. A short ton is 2,000 lb, a long ton is 2,240 lb and a metric tonne is 2,204.6 lb. US steel is almost always quoted per short ton or per cwt. Confirm which one.
• Price per ton read as price per pound. $1,100 per ton typed into a per-pound field multiplies the cost by 2,000.
• Nominal size taken as actual size. HSS names use a nominal wall, but the listed weight is based on a thinner design wall, so a hand formula with the nominal wall reads high.
• One price for everything. Beams, plates, bars and pipe rarely cost the same per pound.
• Theoretical weight read as purchase weight. Rolling tolerance means delivered weight can differ slightly from the table.

Do it faster in Steel Table USA

Everything above is what the app does for you, using the AISC Shapes Database stored on your phone. It works without a signal.

1. Search for a shape such as W12x26 or open one of the twelve categories.
2. Open the menu and type your price per pound once. Every card then shows weight and cost per foot, and everything recalculates.
3. If your supplier charges differently for angles, tap the dollar button on that category and give it its own price. Plate and sheet show dollars per square foot.
4. For bars, flats, plate and sheet, enter your own size and the weight and cost update for that size.
5. Export any list to CSV, JSON or Markdown for your spreadsheet.

Questions people ask

Keep reading

Price a shape in seconds

Steel Table USA is free on Google Play. AISC shapes, your own price per pound, no signal needed.

For reference, not for sign-off. Weights are theoretical, worked from a density of 490 lb per cubic foot, and prices are examples. Rolled shape weights are as shown in Steel Table USA from the AISC Shapes Database v16.0. Delivered weight differs slightly from theoretical weight because of rolling tolerances, so confirm quantities and prices with your supplier before ordering. The AISC Shapes Database is published by the American Institute of Steel Construction. Steel Table USA is an independent app and is not affiliated with or endorsed by AISC.