Metal Weight Calculator

How metal weight is calculated

The mass of any solid object is its volume times its density. For a piece of metal with a constant cross-section, the volume is the cross-sectional area times the length, so every shape in the calculator reduces to the same idea: work out the area of the profile, multiply by the length, multiply by the density.

mass = cross-section area × length × density

With the area in mm² and the length in mm, divide the product by 1,000 to get cm³. Multiply by the density in g/cm³ and the result is in grams. In US units the volume is taken in cubic inches and the density in lb/in³, which gives pounds directly; multiplying by 16 gives ounces.

Using the calculator

1. Choose US units or Metric units. This sets the units of the answer and of the density box.
2. Select the type of product. The form then asks only for the dimensions that shape needs. Each dimension has its own unit, so you can enter a length in meters and a thickness in millimeters.
3. Pick the metal or alloy. Its density is used automatically. If you know the exact density of your material, type it in the density box instead and that value wins.
4. Enter the quantity. The result shows the mass of a single piece and the total for the whole quantity. For heavier totals only the main unit (kg or lb) is displayed.

Supported shapes and their cross-sections

The hexagon's width is the distance between two opposite flat faces, which is the size a spanner or bar stock is quoted by. For the I-profile, r is the inside radius of the web-to-flange fillets and r2 the radius rounding the flange tips; set both to zero for a plain I section.

Some references subtract the corner square of an angle only once, t × (w + h − t). The difference is t², which is under 5 percent of the area for typical angles, so decide which convention suits your supplier's tables if you need to match them exactly.

U-channels and standard sections

Custom U-channels (the "shear and brake press" option) are described by width, height, thickness, flange thickness and a bend radius. Folded sheet-metal channels have one thickness all round, so enter the same value in both thickness boxes. With a radius above zero the section is modelled as a bent strip: web and flanges are straight, joined by two quarter-circle bends measured on the centerline.

Standard channels are different. For the European UPN and UPE series and the American C channels, the calculator reads the section's tabulated cross-sectional area for the type you select and ignores any typed dimensions, which is why the dimension boxes disappear. A longer length simply multiplies that area. The areas follow the published tables (for UPN, DIN 1026-1) closely, so the mass per meter agrees with catalog values for steel of 7.85 g/cm³ to within a small tolerance.

The BC (bar channel) series has parallel flanges of constant thickness, so its area is thickness × (depth + 2 × (flange − thickness)).

Worked examples

Round steel bar. A 25 mm bar, 2 m long, in carbon steel (7.95 g/cm³). Area: π × 25² ÷ 4 = 490.87 mm². Volume: 490.87 × 2,000 = 981,748 mm³ = 981.75 cm³. Mass: 981.75 × 7.95 = 7,805 g, or 7.805 kg.

Aluminum sheet. A sheet 2 m by 1 m and 3 mm thick in aluminum 6061 (2.72 g/cm³). Volume: 2,000 × 1,000 × 3 = 6,000,000 mm³ = 6,000 cm³. Mass: 6,000 × 2.72 = 16.32 kg.

Steel tube. Four lengths of 48.3 mm tube with a 3.2 mm wall, each 6 m long. Inner diameter: 48.3 − 6.4 = 41.9 mm. Area: π ÷ 4 × (48.3² − 41.9²) = 453.4 mm². One length is 453.4 × 6,000 = 2.72 million mm³ = 2,720 cm³, which is 21.63 kg at 7.95 g/cm³, and four weigh 86.5 kg.

US units. A 1 inch round bar, 4 ft (48 in) long: volume π × 0.5² × 48 = 37.70 in³. Steel at 0.2872 lb/in³ gives 10.83 lb, or 173.2 oz. Ten bars are 108.3 lb.

Standard channel. A UPN 100 channel has a tabulated area of 13.5 cm². Six meters of it is 1,350 mm² × 6,000 mm = 8,100 cm³, so 64.4 kg at 7.95 g/cm³.

Densities built into the calculator

Real alloys vary a little between grades and manufacturers, so use the values below as typical figures. If your data sheet gives a different number, type it in the density box.

To convert any density, multiply g/cm³ by 0.036127 to get lb/in³. You can also compute a density yourself from a known mass and volume with the density calculator.

Accuracy and limits

• Rolling tolerances: real bars, plates and sections are made to dimensional and mass tolerances, so a mill's weight can differ from the nominal figure by a few percent.
• Coatings such as galvanizing, and features such as holes, cut-outs and welds, are not included. Break a complex part into simple pieces and add or subtract their masses.
• Radii and chamfers on tubes and rectangular profiles are ignored, so the corners are treated as sharp.
• Check units: a thickness entered in inches where millimeters were meant makes a sheet 25 times too heavy. For other volume figures see the volume calculator.

The results are estimates for purchasing, shipping and design checks. They are not a substitute for structural calculations or manufacturer data. See the disclaimer.