How do you calculate the weight of steel?

Cross-section area in square inches, times 12, times the density in pounds per cubic inch, gives pounds per foot. Carbon steel is 490 lb per cubic foot, or 0.2836 lb per cubic inch, so a 12 sq in section weighs 40.83 lb per foot.

How much does a sheet of 1/4 inch steel plate weigh?

A 4 x 8 ft sheet weighs about 326.7 lb, which is 10.21 lb per square foot, at 490 lb per cubic foot.

What is the density of steel?

490 lb per cubic foot is the figure used for structural carbon steel, given by the Federal Highway Administration's design example as 0.490 kcf from the AASHTO specification. Outokumpu prints 304 stainless at 7.9 and 316 at 8.0 kg/dm³.

Is stainless steel heavier than carbon steel?

Slightly. At 7.9 kg/dm³, 304 stainless is about 0.6% heavier than carbon steel at 490 lb per cubic foot, and 316 at 8.0 is about 1.9% heavier.

How much lighter is aluminum than steel?

6061 aluminum at 2.70 Mg/m³ is about a third of the weight of carbon steel, 0.0975 against 0.2836 lb per cubic inch, for the same piece.

Why is my calculated tube weight higher than the supplier's?

Because the calculation uses sharp corners and nominal wall thickness. Real tube has radiused corners, which remove a little steel, so a calculated weight runs slightly heavy.

How much does copper weigh per foot?

Multiply the cross-section area in square inches by 12 and by copper's density, 0.323 lb per cubic inch on Aurubis's C11000 datasheet. A 1/4 by 1 in copper bar is 0.25 sq in, so 0.25 x 12 x 0.323 = 0.97 lb per foot, about 3.3 times the same bar in aluminum 6061. Choose Copper C11000 as the material above.

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Steel Weight Calculator

490 lb per cu ft carbon steel (AASHTO via FHWA); stainless and aluminum from mill datasheets

Steel weight is cross-section area times length times density. The arithmetic is easy; what almost no steel weight calculator tells you is where its density came from. This one names the document behind each: 490 lb per cubic foot for carbon steel, the figure the Federal Highway Administration's design example takes from the AASHTO specification, and the mill datasheets for 304 and 316 stainless and 6061 aluminum.

Weight of a steel or aluminum piece

Shape

Material

Width, diameter or first side

Second side (tube, angle)

Thickness or wall

Length

Pieces

pcs

Dimensions in inches, length in feet. Second side is used for tube and angle; thickness for plate, pipe, tube and angle.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

The cross-section being weighed

Worked example

A 4 x 8 ft sheet of 1/4 in carbon steel plate.

Area. 48 in wide x 0.25 in thick = 12 sq in of section.
Per foot. 12 sq in x 12 in x 490 lb/ft³ ÷ 1,728 = 40.83 lb per ft.
The sheet. x 8 ft = 326.7 lb, or 10.21 lb per square foot.

A 2 x 2 in tube with a 1/8 in wall weighs 3.19 lb per ft, so ten 20 ft lengths come to 638.0 lb.

The formula

One line, for every shape:

weight per ft = A × 12 × ρ

A: cross-section area in square inches: w × t for plate, πd²/4 for round bar, π/4 (OD² − ID²) for pipe
12: inches in a foot
ρ: density in lb per cubic inch: 490 ÷ 1,728 = 0.2836 for carbon steel

Multiply by the length in feet for a piece, and by the count for an order.

Why the density is the part to check

Every weight calculator does the same multiplication. What differs is the density, and most do not say where theirs came from.

This page uses four, each read from a document with a name, a publisher and a date, and shows them side by side below.

Five densities, and the document each one is printed in

Weight is area times length times density, and the density is the only figure on this page that is not arithmetic. Each one comes from a named, dated document rather than a table copied between calculator sites:

Densities used, converted to imperial where the source printed metric
Material	As printed	lb per cubic inch	lb per cubic foot	Against carbon steel
Carbon steel	490 lb/ft³ (0.490 kcf)	0.2836	490.0	the reference
Stainless steel 304	7.9 kg/dm³	0.2854	493.2	+0.6%
Stainless steel 316	8.0 kg/dm³	0.2890	499.4	+1.9%
Aluminum 6061	2.70 Mg/m³	0.0975	168.6	-65.6%
Copper C11000	0.323 lb/in³ (8.9 g/cm³)	0.3230	558.1	+13.9%

Carbon steel at 490 lb per cubic foot is the figure bridge and building designers use for dead load; the Federal Highway Administration's design example gives it as 0.490 kips per cubic foot, citing the AASHTO specification. Structural steels vary a little by grade, and none of the ones sold for construction varies enough to change a weight you would order by.

The aluminum sheet rounds its own figure. Kaiser's 6061 data sheet prints 2.70 Mg/m³ and, beside it, 0.098 lb per cubic inch. 2.70 Mg/m³ is 0.0975 lb per cubic inch, so the imperial figure on the same line is about half a percent heavy. This page uses the metric figure.

Stainless is not one density. Outokumpu prints 304 at 7.9 and 316 at 8.0 kg/dm³. The difference is the molybdenum in 316, and it is about 1.3 percent.

Plate by the square foot, and why the shapes here run heavy

A square foot of plate is 144 square inches times its thickness times the density. At 490 lb per cubic foot that is 40.8 lb for every inch of thickness:

Weight per square foot, arithmetic from the densities above
Thickness	Carbon steel, lb/sq ft	4 x 8 ft sheet, carbon steel, lb	Aluminum 6061, lb/sq ft
1/8 in	5.10	163	1.76
3/16 in	7.66	245	2.63
1/4 in	10.21	327	3.51
3/8 in	15.31	490	5.27
1/2 in	20.42	653	7.02
3/4 in	30.62	980	10.53
1 in	40.83	1307	14.05

The shapes on this page are ideal ones. A tube is calculated with sharp corners and an angle without the rounded fillet at its root. Real tube has radiused corners, so it carries a little less steel than the rectangle-minus-rectangle arithmetic, and a calculated weight errs heavy. For a rolled wide-flange beam, the steel beam calculator on this site works the same way and shows the gap against the published section.

Nominal is not actual. Pipe is sold by a nominal size that is not its outside diameter, and tube wall thickness is a nominal figure too. Measure the outside diameter and the wall, or read them from the supplier's sheet, and enter those.

The sources

Read 2026-09-14.

LRFD Design Example for Steel Girder Superstructure Bridge, FHWA NHI-04-041, Federal Highway Administration and National Highway Institute, prepared by Michael Baker Jr., Inc., December 2003. Design data: steel density 0.490 kcf, citing AASHTO LRFD Table 3.5.1-1.

Outokumpu Core range datasheet, stainless steels for corrosive environments, Outokumpu, document 1560EN:4, November 2022. Physical properties: Core 304/4301 density 7.9 kg/dm³, printed as 0.285 lbm/in³.

Outokumpu Supra range datasheet, stainless steels for highly corrosive environments, Outokumpu, document 1561EN:4, November 2022. Physical properties: Supra 316/4401 density 8.0 kg/dm³, printed as 0.289 lbm/in³.

Sheet, Coil and Plate Alloy 6061 Technical Data, Kaiser Aluminum, Rev. 05/06. Typical physical properties: nominal density 2.70 Mg/m³, printed as 0.098 lbs/in³.

Technical Datasheet C11000 (Cu-ETP), US, Aurubis, undated datasheet read 2026-09-15. Physical properties: density 0.323 lb/in³ and 8.9 g/cm³; applicable specifications ASTM B152, B370.

Frequently asked questions

How do you calculate the weight of steel?: Cross-section area in square inches, times 12, times the density in pounds per cubic inch, gives pounds per foot. Carbon steel is 490 lb per cubic foot, or 0.2836 lb per cubic inch, so a 12 sq in section weighs 40.83 lb per foot.
How much does a sheet of 1/4 inch steel plate weigh?: A 4 x 8 ft sheet weighs about 326.7 lb, which is 10.21 lb per square foot, at 490 lb per cubic foot.
What is the density of steel?: 490 lb per cubic foot is the figure used for structural carbon steel, given by the Federal Highway Administration's design example as 0.490 kcf from the AASHTO specification. Outokumpu prints 304 stainless at 7.9 and 316 at 8.0 kg/dm³.
Is stainless steel heavier than carbon steel?: Slightly. At 7.9 kg/dm³, 304 stainless is about 0.6% heavier than carbon steel at 490 lb per cubic foot, and 316 at 8.0 is about 1.9% heavier.
How much lighter is aluminum than steel?: 6061 aluminum at 2.70 Mg/m³ is about a third of the weight of carbon steel, 0.0975 against 0.2836 lb per cubic inch, for the same piece.
Why is my calculated tube weight higher than the supplier's?: Because the calculation uses sharp corners and nominal wall thickness. Real tube has radiused corners, which remove a little steel, so a calculated weight runs slightly heavy.
How much does copper weigh per foot?: Multiply the cross-section area in square inches by 12 and by copper's density, 0.323 lb per cubic inch on Aurubis's C11000 datasheet. A 1/4 by 1 in copper bar is 0.25 sq in, so 0.25 x 12 x 0.323 = 0.97 lb per foot, about 3.3 times the same bar in aluminum 6061. Choose Copper C11000 as the material above.

Check these numbers yourself

LRFD Design Example for Steel Girder Superstructure Bridge, FHWA NHI-04-041Federal Highway Administration and National Highway Institute, prepared by Michael Baker Jr., Inc., December 2003. Design data: steel density 0.490 kcf, citing AASHTO LRFD Table 3.5.1-1.
Outokumpu Core range datasheet, stainless steels for corrosive environmentsOutokumpu, document 1560EN:4, November 2022. Physical properties: Core 304/4301 density 7.9 kg/dm³, printed as 0.285 lbm/in³.
Outokumpu Supra range datasheet, stainless steels for highly corrosive environmentsOutokumpu, document 1561EN:4, November 2022. Physical properties: Supra 316/4401 density 8.0 kg/dm³, printed as 0.289 lbm/in³.
Sheet, Coil and Plate Alloy 6061 Technical DataKaiser Aluminum, Rev. 05/06. Typical physical properties: nominal density 2.70 Mg/m³, printed as 0.098 lbs/in³.
Technical Datasheet C11000 (Cu-ETP), USAurubis, undated. Read 2026-09-15. Physical properties: density 0.323 lb/in³ and 8.9 g/cm³.

How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-14. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

A calculated weight, not a mill certificate. Shapes are idealized with sharp corners and nominal dimensions, so real tube and angle weigh slightly less. Densities are read from the documents named on the page on 14 September 2026.