All of it is one formula
Every figure on this page comes from cross-sectional area times length times density. There is no shape factor and no fudge. What changes between a round bar and a piece of angle is only how you work out the area, and the arithmetic for that is short enough to do on a scrap of cardboard:
| Shape | Cross-section area (in²) |
|---|---|
| Plate, sheet, flat bar | width x thickness |
| Round bar | 0.7854 x diameter² |
| Square bar | side² |
| Round tube | 0.7854 x (OD² - ID²), where ID = OD - 2 x wall |
| Square tube | OD² - (OD - 2 x wall)² |
| Angle | (leg A x t) + ((leg B - t) x t) |
Multiply that by the length in inches to get cubic inches, then by the density in pounds per cubic inch. A one inch square bar of mild steel twelve inches long is 1 x 1 x 12, which is 12 cubic inches, times 0.2836, which is 3.40 pounds. If you remember only one number from this page, remember that one: a foot of one inch square steel is three and a half pounds, near enough, and everything else scales off it by area.
Densities, and how much they actually vary
The figures used here are the common nominal values. They are good enough for ordering, for lifting plans and for quoting, and they are not good enough for anything that needs a mill certificate.
| Material | lb/in³ | g/cm³ | Normal range |
|---|---|---|---|
| Mild steel (A36, 1018) | 0.2836 | 7.85 | 7.80-7.90 |
| Stainless 304 / 316 | 0.289 | 8.00 | 7.90-8.03 |
| Aluminum 6061 | 0.0975 | 2.70 | 2.68-2.71 |
| Aluminum 5052 | 0.0968 | 2.68 | 2.66-2.70 |
| Brass C360 | 0.307 | 8.50 | 8.40-8.55 |
| Copper C110 | 0.323 | 8.94 | 8.89-8.96 |
Alloy content moves density more than temper does. A 6061-T6 bar and a 6061-T0 bar of the same size weigh the same to any scale you own, because heat treatment rearranges the microstructure rather than the mass. Switching from 6061 to 7075 or from 304 to a duplex grade moves it by a percent or so. What moves the weight of a real piece far more than any of this is mill tolerance on thickness, which on hot rolled plate can be several percent on the thin dimension and is always allowed to run over as well as under.
Where the sharp-corner assumption costs you
Two shapes on this page are modelled with square corners that the real product does not have. Square and rectangular tube is roll-formed, so the outside corners carry a radius of roughly twice the wall thickness and the corner wall thins slightly as it forms. That makes real tube run about two to four percent lighter than the sharp-corner calculation. Rolled structural angle goes the other way: it has a fillet at the inside root that adds material, partly offset by taper on the leg tips, and on common sizes the net is usually a percent or two heavy.
If the number is going into a shipping quote or a crane chart, use the supplier's published weight per foot for that specific product rather than this. Their table is measured from the actual roll geometry. If the number is going into a decision about whether you can carry it, whether the bench will hold it, or how much stock to buy, the difference is noise.
Pipe is not tube
The round tube option asks for outside diameter and wall, which is exactly how tube is sold. Pipe is not sold that way. A piece of 2 inch schedule 40 pipe has an outside diameter of 2.375 inches and a wall of 0.154 inches, and neither of those numbers is 2. Nominal pipe size is a name, not a dimension, and it stopped matching the actual bore a very long time ago. Look up the OD and wall for the size and schedule you have, put those in, and the answer will be right. Put the nominal size in as the OD and you will underweight the piece by a third.
Buying by the pound
Structural steel, plate and most bar stock are priced by the pound at the mill and by the pound or the foot at the service center, which is why this page carries a price field. Two things it deliberately does not model. The first is drops: if you need 40 inches out of a 20 foot stick, most suppliers will sell you the cut piece at a premium over the per-pound rate, or sell you the whole stick, and either way the invoice is not weight times price. The second is that stainless, brass and copper move with commodity markets on a scale that makes any figure printed here stale within weeks. Get the current quote, put it in the field, and let the arithmetic do the rest.
Questions people ask
How much does a foot of 1 inch square steel bar weigh?
About 3.40 pounds. The cross-section is one square inch, twelve inches of it is twelve cubic inches, and mild steel is 0.2836 pounds per cubic inch, giving 3.403 pounds. That is a useful anchor because everything else scales by area against it. Half inch square bar is a quarter of the area, so 0.85 pounds a foot. Two inch square bar is four times the area, so 13.6 pounds a foot. One inch round bar is 0.7854 square inches, so it is 2.67 pounds a foot, which is the reason round stock always feels lighter than you expect next to square of the same nominal size.
Why is my supplier's weight per foot different from this?
Usually one of three reasons. For square and rectangular tube, their figure accounts for the corner radii and this one does not, so theirs will be two to four percent lighter. For structural angle and channel, their figure comes from the actual rolled section with its root fillet, and this sharp-corner calculation is close but not identical. For plate and sheet, mill thickness tolerance is real and their table may quote a nominal weight that the delivered material does not match. When it matters, their number is the one to use, because it describes the product they are actually shipping.
Does temper or heat treatment change the weight?
Not measurably. 6061-T6 and 6061-T0 have the same density, as do annealed and cold-worked 304. Heat treatment and cold work change the arrangement and dislocation density of the crystal structure, and the mass change is far below anything you could weigh. What does change density is alloy composition, and that is a matter of a percent or two between grades within a family and rather more between families. Pick the closest listed material and do not lose sleep over the third decimal.
How do I work out the weight of a shape that is not on the list?
Break it into rectangles and circles, work out the area of each, add and subtract as appropriate, then multiply by length and density. A channel is two flanges plus a web. A hexagonal bar is 0.866 times the distance across flats squared. A tee is a flange plus a stem, minus nothing if you count the overlap once. For anything genuinely awkward, most CAD packages will report the mass of a solid directly once you assign a material, and that will be more accurate than any decomposition you do by hand.
Can I use this for a lifting plan?
For rough planning yes, for the actual rigging no. This gives the weight of clean stock at nominal dimensions. A real lift involves the weight of anything already welded to it, paint, scale, water in a tube, the weight of the rigging itself, and a margin for the fact that nobody weighed it. Rigging is governed by rated capacities, sling angles and a competent person signing off, and none of that comes out of a density calculation. Use this to decide whether something is a two-person carry or a forklift job, and use a scale or an engineer for anything that goes overhead.