Steel weighs 490 lb per cubic foot (7,850 kg per cubic meter), so the weight is the volume times that density: a 4 ft by 8 ft steel plate 1/4 in thick has 0.667 cubic feet of steel and weighs 326.7 lb, which is 10.2 lb per square foot.
How to calculate the weight of steel
Weight = cross-section area × length × density, with carbon steel at 490 lb/ft³ (7,850 kg/m³)
Pick the shape, enter its size and length, and the calculator finds the cross-section area, multiplies it by the length for a volume, and by the density for the weight. 7,850 kg per cubic meter is the density given for ASTM A992 structural steel, which is 490 lb per cubic foot. Stainless 304 is denser at 7,900 kg per cubic meter, so a stainless part weighs about 0.6% more: the same plate is 328.8 lb.
Steel plate and sheet weight
Plate weight scales with thickness. One square foot of steel 1 in thick weighs 490 ÷ 12 = 40.8 lb, so multiply by the thickness in inches.
| Thickness | Weight per sq ft | 4 x 8 ft sheet (32 sq ft) |
|---|---|---|
| 1/8 in | 5.1 lb | 163 lb |
| 3/16 in | 7.7 lb | 245 lb |
| 1/4 in | 10.2 lb | 327 lb |
| 3/8 in | 15.3 lb | 490 lb |
| 1/2 in | 20.4 lb | 653 lb |
| 3/4 in | 30.6 lb | 980 lb |
| 1 in | 40.8 lb | 1,307 lb |
Steel bar weight: round, square and flat
A round bar has an area of π ÷ 4 × d², so a 1 in bar is 0.785 sq in and weighs 2.67 lb per foot; 10 ft is 26.7 lb. A square bar of 1 in has 1 sq in and weighs 3.40 lb per foot. A flat bar 2 in by 1/4 in is 0.5 sq in, or 1.70 lb per foot, so a 10 ft length is 17.0 lb. A quick rule: one square inch of steel section weighs 3.4 lb per foot.
Steel tube and pipe weight
For tube and pipe the cross-section is the outside shape minus the hollow. A 2 in square tube with a 1/8 in wall has 4 - 1.75² = 0.94 sq in, or 3.19 lb per foot. Real tube has rounded outside corners and holds a little less steel, so the calculator reads a few percent heavy; use the mill's weight per foot for a quote. Round pipe uses the outside diameter, not the pipe size: 2 in pipe is 2.375 in across, and with a 0.154 in wall it weighs 3.66 lb per foot, so a 21 ft length is 76.8 lb.
I-beam and W-shape weight
A wide flange shape is named by its depth and weight per foot: W8x18 is about 8 in deep and weighs 18 lb per foot, so a 20 ft beam is 360 lb. Choose the I-beam shape, pick a common size or type the number after the x, and enter the length. The metric names work the same way: a W200x27 is 27 kg per meter. To size a beam for a load, use the steel beam calculator.
Steel weight in kg
Every result is given in both systems. 326.7 lb is 148.2 kg, and the density used is shown so you can check it. One US ton is 2,000 lb, so 326.7 lb is 0.163 tons; a tonne is 1,000 kg.
Truck and trailer payload
A truck's payload is its GVWR minus its curb weight (Knapheide). A 2,000 lb payload carries six of the 327 lb sheets above and no more. Federal limits on the Interstate are 80,000 lb gross, 20,000 lb per single axle and 34,000 lb on a tandem axle (23 CFR 658.17). The calculator counts the trips for a payload you enter.
Related calculators
Weigh the concrete that goes with the steel with the concrete weight calculator, count reinforcement bars with the rebar calculator, and convert other materials with the cubic yards to tons calculator. Add up cut lengths with the feet and inches calculator. More are in measuring and planning calculators.