Sheet metal weight. With the right density.

01 — The mathsVolume times density, nothing more.

The weight of a sheet is its volume multiplied by the density of the material. For a rectangular sheet the volume is length × width × thickness; density is a material constant, given in kg/dm³ (the same as g/cm³) or in kg/m³.

The formula works as written because one millimetre of thickness over one square metre is exactly one cubic decimetre. Hence the shortcut every workshop knows by heart: one square metre of 1 mm carbon steel weighs 7.85 kg. Any other thickness is a multiplication away.

Stainless, aluminium, copper and brass follow the same rule — only the density changes. What really moves the number are the real-world cases: holes, coating, the raised pattern of tread plate, the profile of a corrugated sheet. That is exactly where a calculation done on a plain rectangle starts to drift.

02 — DensitiesWhere the numbers come from, and why 7,850.

Every density we use has a stated source:

Steel deserves a note. Some calculators use 7,960 kg/m³ — a figure that sits inside the physical range of carbon steels (7,750-8,050) but is not the one sheets are bought and invoiced with. The conventional value is 7,850 kg/m³, prescribed by Eurocode 3 (EN 1993-1-1) for structural steelwork.

The gap is 1.4%: small on one sheet, less small on an order. On a two-tonne pack that is 28 kg of difference — enough to put a delivery note and an invoice at odds. So we use 7.85, and still leave a custom density field: if your supplier states a different figure, theirs wins over ours.

03 — The tableWeight per square metre, thickness by thickness.

If the question is simply how much a 3 mm sheet weighs, there is nothing to fill in — just read it off. Values are per square metre, plain uncoated sheet.

Values in kg/m². For a whole sheet multiply by the area in square metres: a 3 mm sheet in the 2,000 × 1,000 mm format covers 2 m² and therefore weighs 47.10 kg.

04 — Real casesGalvanising and tread plate.

Galvanising. The zinc coating adds weight and has to be counted. Standard EN 10346 states it as a Z followed by the grams per square metre across both faces: Z275 means 275 g/m², that is 0.275 kg added to the bare steel. On 0.8 mm galvanised sheet the sum is 6.28 + 0.275 = 6.555 kg/m². Small in percentage, clearly visible across a large roof area.

Tread plate. Chequer or tread plate carries a raised anti-slip pattern that weighs. The counter-intuitive part is that this added weight does not scale with thickness: the pattern is always the same, so it always adds the same amount of material. Comparing the UNI 4630 commercial tables against plain sheet of the same base thickness, the surcharge is constant at roughly 2.5 kg/m²:

Values in kg/m². Watch one ordering trap: when a plate is quoted as 3+2 the first figure is the base thickness and the second the height of the pattern. It is not a 5 mm plate — it weighs considerably less.

Holes. The calculator subtracts holes and cut-outs from the area before applying the weight per square metre. On a perforated panel or a blank with repeated slots the difference is far from negligible, and calculators that only weigh the full rectangle simply miss it.

05 — CorrugatedWhy thickness alone is not enough.

Corrugated or profiled sheet cannot be weighed like flat sheet, because it is not flat. The profile is roll-formed from a strip wider than the covering width you see once installed: covering one square metre takes more than one square metre of steel.

The development factor is the ratio between the starting strip width and the effective covering width of the finished profile. There is no universal value: it depends on rib height, pitch and rib geometry, and it changes from profile to profile. A roofing sheet sits at the low end; a composite floor deck, with tall closely spaced ribs, sits considerably higher.

That is why this calculator asks for the factor instead of inventing one: you will find it on the datasheet of the profile you are buying, or you can derive it by dividing strip width by covering width. A calculator that hands you the weight of "a corrugated sheet" without knowing which profile you hold is handing you a made-up number.

06 — Next stepFrom weight to bending.

Weight is what you need to buy, ship and handle the material. But if that sheet is also going to be bent, the figures you have just entered — thickness, material and length — are exactly the ones needed to work out bending force. Same starting point.

Bending parameters gives you tonnage, recommended V-die, inner radius and minimum flange, with the suggested PG machine. The Bending rule shows every usable die for that thickness. Bend allowance tells you how much material to cut before bending — and at that point you come back here to weigh it.