Metal Weight Calculator

Metal weight = volume × density

Every metal weight comes from one rule: work out the volume of the shape from its dimensions, then multiply by the density of the metal. For mild steel the density is about 7,850 kg/m³, so a 1 m × 1 m × 10 mm steel plate weighs 1 × 1 × 0.01 × 7850 = 78.5 kg. Change the metal and only the density changes — the same plate in aluminium (2,700 kg/m³) is just 27 kg.

That single idea is why this metal weight calculator can cover so many shapes and metals: each shape just has its own way of getting the volume, and the density does the rest. Because the weight is computed from the dimensions you enter rather than read from a fixed chart, it works for any size — standard or odd — and for steel, stainless, aluminium, copper, brass, titanium or a custom alloy density you type in.

What this calculator does — and its lane

This is the multi-shape metal and steel weight calculator for solid bars, flats, plate and sheet, non-round hollow sections (square and rectangular tube), structural shapes (angle, channel, beam), discs and rebar. The one thing it deliberately leaves out is round pipe and round tube — those are a hollow cylinder defined by outside diameter and wall, and they live in the dedicated pipe weight calculator so each tool stays the clearest answer for its shape. It does not do strength, load or section-modulus — this is mass, not structural capacity. The honest friction with any weight calculator: the number is theoretical, so for buying or load checks confirm against a mill certificate.

Steel and metal plate / sheet weight

Plate, sheet and flat stock are the simplest case because they are rectangular: weight = length × width × thickness × density. For sheet you often want the figure per square metre or per square foot, which drops the length and width and is just thickness × density — for steel a handy result is that plate weighs thickness in mm × 7.85 kg/m², so 10 mm steel plate is 78.5 kg/m². The tool reports the total weight and the per-area weight together, and the same maths covers MS plate, GI and galvanized sheet, stainless (SS) sheet and plate, aluminium sheet, iron plate and CR / HR sheet — only the density changes.

For chequer (checker / chequered / tread) plate, the calculator computes the base flat-plate weight and then adds an editable raised-pattern allowance in kg/m², because the diamond or teardrop pattern adds a little metal on top of the flat sheet. The default allowance is a small typical value you can change to match your plate — nothing proprietary is reproduced.

Round, square, flat and hex bar weight

Solid bars are an area times a length. A round bar is π/4 × diameter² × length; a square bar is side² × length; a flat bar or strip is width × thickness × length; and a hexagonal bar measured across the flats is 0.866025 × (across-flats)² × length. Multiply any of these areas by the density and you have the weight per unit length and the total. A 25 mm steel round bar one metre long weighs about 3.85 kg, which matches the steel shortcut below.

For steel round bar (and rod) there is a tidy cross-check: weight in kg/m = d² / 162.2, with the diameter d in millimetres. So a 12 mm bar is 12²/162.2 ≈ 0.888 kg/m and a 25 mm bar is 25²/162.2 ≈ 3.85 kg/m. That constant is simply π/4 × 7850 expressed for millimetres, so it is steel-specific; the general volume × density method works for any metal because you supply the density.

Square and rectangular tube (hollow section) weight

A hollow square or rectangular tube is the outer area minus the bore. For a square tube (SHS) of side a and wall t the metal area is a² − (a − 2t)²; for a rectangular tube (RHS) of width b and height h it is b×h − (b − 2t)(h − 2t); multiply by length and density for the weight. People often call these square pipe or box section — a 50 × 50 × 3 mm steel SHS works out to a 564 mm² metal area, about 4.43 kg/m. One honest caveat: real hot-formed and cold-formed hollow sections have rounded corners, so the true weight per metre runs a few percent below this sharp-corner figure; it is an excellent estimate, not the published section weight to the gram.

If your tube is round rather than square or rectangular, it is the same hollow-cylinder calculation as a pipe — use the pipe weight calculator for round tube and round pipe.

Angle, channel and beam weight

Structural shapes are still area × length × density; the only trick is the cross-sectional area. An angle (L), equal or unequal, is closely approximated by (leg a + leg b − thickness) × thickness — a 50 × 50 × 6 mm angle is about 564 mm², roughly 4.43 kg/m. A channel (C section) is the web plus two flanges: web depth × web thickness + 2 × (flange width − web thickness) × flange thickness. An I-beam or H-beam is two flanges plus the web between them: 2 × (flange width × flange thickness) + (depth − 2×flange thickness) × web thickness. These give a clean theoretical weight from your dimensions; rolled sections have fillets and rounded toes the formula ignores, so treat the result as an estimate and check the published weight per foot for buying.

Rebar / TMT bar weight per metre

Reinforcement bar (rebar, TMT, sariya, steel rod) is treated as a solid round bar: π/4 × diameter² × length × density. The famous shortcut for steel is the same one as for round bar — kg/m = d² / 162.2 with d in mm — so 8 mm rebar is about 0.395 kg/m, 12 mm about 0.888 kg/m, 16 mm about 1.58 kg/m and 25 mm about 3.85 kg/m. The calculator shows this d²/162.2 figure next to the full density result so you can sanity-check a bar bending schedule at a glance.

Metal density chart

Density is the only material-specific number in the whole calculation, so getting it right is what makes the weight match your real metal — using the steel value for aluminium or titanium overestimates badly. The presets below are typical published densities and are editable for a specific alloy or grade. The pound-per-cubic-inch and pound-per-cubic-foot columns are the same densities in US units.

Two steel quick-references worth memorising: steel plate is thickness mm × 7.85 kg/m², and steel round bar (or rebar) is d² / 162.2 kg/m with d in mm. Spelling note for searchers: aluminium and aluminum are the same metal, MS means mild steel and SS means stainless, and the figures are identical whether you read per metre or per foot, kg or lb — the tool gives both at once.

Weight in kg and pounds, per metre and per foot

Whatever shape and metal you pick, the result is shown in kilograms and pounds together; for the long shapes (bars, tubes, angle, channel, beam, rebar) you also get weight per metre and per foot, and for plate and sheet you get weight per square metre and per square foot. Set a quantity to total a batch of identical pieces, and if you enter your own price per kg or per lb the calculator adds a cost line — the price is yours, nothing is built in.

Worked examples

Example 1 — steel plate

A 1 m × 1 m sheet of 10 mm mild steel: 1 × 1 × 0.01 × 7850 = 78.5 kg, or 78.5 kg/m². The same plate in aluminium is 27 kg. Open it with ?shape=plate&mat=2700&l=1&w=1&t=10&unit=m&tunit=mm style parameters via the share link.

Example 2 — square tube vs angle

A 50 × 50 × 3 mm steel square tube has a metal area of 50² − 44² = 564 mm², so about 4.43 kg/m. A 50 × 50 × 6 mm equal angle works out to the same 564 mm² area and 4.43 kg/m — a neat coincidence that shows the area drives everything.

Metal weight calculator FAQ