Steel and Plate Weight Calculator

How it works

The mass of a uniform bar is its cross-section area times its length times the density of the material.

m = A × L × ρ

The area comes from the shape: plate w × t; round bar π d² ÷ 4; square bar d²; hexagon (across flats s) √3 ÷ 2 × s²; round tube π ÷ 4 (D² − (D − 2t)²); rectangular tube a b − (a − 2t)(b − 2t); equal angle t (2a − t). The result is the nominal mass: mill tolerances on thickness and the exact alloy change it by a percent or two. Material properties are on Material Properties.

Worked example

A carbon-steel plate 1 500 mm × 3 000 mm × 10 mm: A = 1.5 × 0.010 = 0.015 m², volume = 0.015 × 3 = 0.045 m³ and mass = 0.045 × 7 850 = 353.3 kg, which is 78.5 kg per m² of 10 mm plate (7.85 kg per m² per mm of thickness).

DN80 (3 in) schedule 40 pipe, outside diameter 88.9 mm, wall 5.49 mm: A = π ÷ 4 × (88.9² − 77.92²) = 1 439 mm², so the mass is 1 439×10⁻⁶ × 7 850 = 11.29 kg per meter (the standard table says 11.3). A round bar of 50 mm diameter and 6 m long weighs 92.5 kg.

Things to know

The result is the theoretical weight. Mill and structural sections are sold by weight, and the actual weight is usually within 3 to 5 percent above or below, depending on the standard.

Plate thickness tolerances can be −0.3 to +1 mm or more; cut-to-length and flame-cut parts lose the kerf.

Alloy density varies a little: stainless 304 is 8 000 kg/m³ but 316 is 8 000, and duplex 7 800; 6061 aluminum 2 700 and 7075 2 810. Enter the exact density for critical work.

Add the weight of welds, coatings and galvanizing (about 3 to 6 percent for hot-dip zinc) when weighing fabricated parts.

To find the weight of a section not listed (I-beams, channels), use the area from the supplier’s table in the “Other” calculation: area times density gives the mass per meter.

Common questions

How much does a square meter of steel plate weigh?

7.85 kg per millimeter of thickness: 10 mm plate weighs 78.5 kg/m², 6 mm plate 47.1 kg/m².

How do I find the weight of a steel pipe?

Use the round tube option with the outside diameter and wall thickness, or the rule of thumb m = 0.02466 × t × (D − t) kg per meter with D and t in millimeters for carbon steel.

Is aluminum really one third of the weight of steel?

Yes, by volume: 2 700 against 7 850 kg/m³. Aluminum is also about one third as stiff, so a stiffness-critical part is not lighter by that factor.

Sources

• ASTM A6/A6M and EN 10029 (plate tolerances); ASME B36.10M (pipe dimensions); EN 10305, EN 10210 (tubes).
• Machinery’s Handbook, Industrial Press (densities, weights of materials and sections).

Last reviewed: November 2, 2026