At a glance
| Metal | Density, g/cm³ (= kg per m² for each 1 mm) | kg per m² at 3 mm | Where the figure comes from |
|---|---|---|---|
| Aluminium (6082, 5251 and pure) | 2.70 | 8.1 | 6082 datasheet 2.70; 5251 datasheet 2.69; stockholder's table 2.70 |
| Mild steel | 7.85 | 23.6 | Usual round figure; a stockholder's comparative table prints 7.8 |
| Stainless, ferritic (430) | 7.75 | 23.3 | Stockholder's table 7.75; TL-MET-18 notes 7.7 |
| Stainless 304 | 7.90 | 23.7 | Euro Inox table of properties (2007); stockholder prints 7.92 for austenitic |
| Stainless 316 | 8.00 | 24.0 | Euro Inox table of properties (2007) |
| Copper | 8.90 | 26.7 | Stockholder's table 8.90; copper CW024A datasheet 8.92 |
| Brass | 8.45 | 25.4 | Brass CW508L 8.44, CZ121 8.5, stockholder's generic brass 8.47 |
| Bronze, generic | 8.89 | 26.7 | Stockholder's table; phosphor bronze PB102 datasheet 8.85 |
Typical values for planning, not guarantees: grade, temper and tolerance move them. Weight in kg per m² equals thickness in mm times density in g/cm³. Confirm with the mill certificate or the partner's datasheet before any weight that matters, such as a lift plan or a load on a floor.
One sum: thickness times density
A sheet 1 mm thick and 1 m square holds one litre of metal per square metre, so its mass in kilograms is the density in g/cm³. So the density column of the table above is also the weight of a square metre for each millimetre of thickness. Multiply by the thickness in millimetres and by the area in square metres and you have the weight of any flat panel.
- Aluminium is the outlier. At 2.70 it is about a third of the weight of steel, stainless steel, brass, copper or bronze, which sit between 7.7 and 8.9. Mild steel and stainless are within about one per cent of each other, so a stainless panel weighs about what the same steel panel does.
- The copper alloys are the heavy ones. Brass at about 8.45 and copper at about 8.9 are 8 to 13 per cent heavier than steel. Source values differ in the second decimal place: brass is 8.44 in one datasheet, 8.5 in another table; copper 8.90 in one table and 8.92 in a datasheet for one grade. The spread is under 1 per cent and does not matter for planning.
- Bronze is a family. The stockholder's general table prints one bronze figure of 8.89 and a phosphor bronze datasheet gives 8.85. An aluminium bronze is lighter: a US table in our research gives about 7.6 for one cast grade, which we have not verified. Name the alloy before relying on a bronze weight.
For other thicknesses, the table below is the same sum done for you.
| Metal | 1 mm | 1.5 mm | 2 mm | 3 mm | 5 mm |
|---|---|---|---|---|---|
| Aluminium | 2.7 | 4.1 | 5.4 | 8.1 | 13.5 |
| Mild steel | 7.9 | 11.8 | 15.7 | 23.6 | 39.3 |
| Stainless, ferritic | 7.8 | 11.6 | 15.5 | 23.3 | 38.8 |
| Stainless 304 | 7.9 | 11.9 | 15.8 | 23.7 | 39.5 |
| Stainless 316 | 8.0 | 12.0 | 16.0 | 24.0 | 40.0 |
| Copper | 8.9 | 13.4 | 17.8 | 26.7 | 44.5 |
| Brass | 8.5 | 12.7 | 16.9 | 25.4 | 42.3 |
| Bronze, generic | 8.9 | 13.3 | 17.8 | 26.7 | 44.5 |
Bar, tube and section formulas
A UK stockholder prints the formulas below in its general data pages, with density ρ in kg/dm³ (the same number as g/cm³) and dimensions in millimetres. They are theoretical weights calculated from nominal dimensions, and the stockholder says that in practice the actual weight can vary significantly from the theoretical weight, because of manufacturing tolerances and compositions.
| Form | Dimensions in mm | Weight | Result |
|---|---|---|---|
| Plate or sheet | t = thickness (mm) | t x ρ | kg per m² |
| Plate or sheet, one piece | L, w, t (mm) | 0.000001 x L x w x t x ρ | kg per sheet |
| Round bar | d = diameter | 0.0007854 x d² x ρ | kg per m |
| Square bar | a = side | 0.001 x a² x ρ | kg per m |
| Hexagon bar | f = across flats | 0.00086603 x f² x ρ | kg per m |
| Flat bar | w = width, t = thickness | 0.001 x w x t x ρ | kg per m |
| Angle or tee | L1, L2 = legs, t | 0.001 x (L1 + L2 - t) x t x ρ | kg per m |
| Round tube | D = outside diameter, t = wall | 0.0031416 x (D - t) x t x ρ | kg per m |
| Square or rectangular tube | a1, a2 = sides, t = wall | 0.001 x (2 a1 + 2 a2 - 4 t) x t x ρ | kg per m |
Two cautions. First, the tube formulas ignore the rounded corners and the weld seam, so a manufacturer's table for the actual section is a little lower; use the formula to size a lift or compare options, and the table for a figure you will quote. Second, the formula gives the weight of the metal only. A bar top that is sheet wrapped over a core, a door leaf with a frame, or a base with a plinth plate all need each part added from its own datasheet.
Six worked examples
Each result is computed from the densities and formulas above; the working is shown so that you can repeat it with your own dimensions.
| Item | Working (ρ in kg/dm³) | Result | Remember | |
|---|---|---|---|---|
| A | Table frame in 25 x 25 x 2 mm square tube, 6.0 m of tube in all | 0.001 x (50 + 50 - 8) x 2 x 7.85 | 1.44 kg per m, so 8.7 kg | Tube has rounded corners: a table gives slightly less. |
| B | Brass door panel, 2040 x 726 mm, 3 mm sheet | 0.000001 x 2040 x 726 x 3 x 8.45 | 37.5 kg (2 mm: 25.0 kg) | Sheet only. Add the core, frame and hinges. |
| C | Stainless 304 sheet, 2400 x 1200 mm, 2 mm | 0.000001 x 2400 x 1200 x 2 x 7.90 | 45.5 kg | A full sheet is a two-person lift at the least: plan it. |
| D | Brass round bar, 20 mm diameter | 0.0007854 x 20² x 8.45 | 2.65 kg per m | A handrail or leg is heavier than it looks. |
| E | Stainless 316 round tube, 50.8 mm outside diameter, 1.5 mm wall | 0.0031416 x (50.8 - 1.5) x 1.5 x 8.00 | 1.86 kg per m | A handrail run: multiply by its length. |
| F | The same 2400 x 1200 x 3 mm panel in aluminium and in mild steel | 0.000001 x 2400 x 1200 x 3 x ρ | aluminium 23.3 kg, steel 67.8 kg | Aluminium is about a third of the weight. |
Example A in detail: the figure shows how the section turns into a weight per metre.
From weight to decisions
The weight is only the start. Ask, in this order:
- What is the heaviest single lift? Not the total. A 3 mm brass door panel of 38 kg is one lift; a full 2400 x 1200 mm 2 mm stainless sheet of 46 kg is another. Say on the drawings which pieces are lifted whole, and ask the partner to agree the handling method with the contractor. Handling limits come from the HSE and the employer's own assessment, not from this sheet; we have not quoted any.
- What carries it? Give the fixing supplier or the engineer the weight and where it acts. A wall panel hangs from its fixings and the substrate behind them; a table base stands on its feet. Divide the weight between the fixings or feet that really carry it, and allow for the load being uneven.
- What does it add to the floor? Convert mass to force: 150 kg is 1.47 kN (taking g as 9.81 m/s²), or about 0.37 kN on each of 4 feet. A floor's allowable loading is set by the structure and the design codes (BS EN 1991-1-1 and its National Annex), which we have not read, and a heavy base or counter on a small footprint is a point load that a structural engineer should check. Do not compare a total with a floor figure on a drawing.
- What does it weigh in the crate? Add packaging, a pallet or crate and any protection, then check the route: lift capacity, stairs, doors and the delivery vehicle. See our delivery access survey and packaging and crating specification.
Why the answer is approximate
- Thickness is nominal. Sheet is bought to a tolerance, and polishing or grinding removes metal. Say whether the thickness is before or after finishing, and see sheet metal thickness and gauge conversion; never write a gauge number without millimetres.
- Holes and folds change the sum. A perforated or expanded sheet weighs less than a solid one by roughly its open area, and a folded edge or return adds metal. See perforated, laser-cut and expanded metal.
- Alloys and tempers differ. Use the density for the alloy named in the specification, not the family.
- Metals move with heat as well as load. Weight is not the only sizing check: see thermal expansion of metals for movement.
Specification wording
Paste into your schedule or specification and replace anything in [square brackets] with your own figures. Wording is a starting point: your specification governs.
Partner to state, before shop drawings are approved, the estimated weight of each [assembly / panel / base] and of the heaviest single lift, calculated from the finished thickness [in mm], the dimensions and the density of the alloy named, giving the density used. Weights are estimates; the as-built weight to be confirmed by weighing [one sample / each item].
Fixings for [element] to be designed by [the partner / a named engineer] for a self-weight of [ ] kg and a [ ] kg imposed load, acting at [positions]. Where the base stands on [a raised or timber floor], the partner to give the weight and the size of each foot so that the floor can be checked by [the structural engineer].
Weights of [wrapped or cored] items to include the core, adhesive, edge trim and hardware. The partner to list each component's thickness and material in the weight statement.
Terms used on this page
- Density
- The mass of a material per unit of volume. For metals it is usually given in grams per cubic centimetre (g/cm³) or kilograms per cubic decimetre (kg/dm³), which are the same number; multiplied by 1,000 it is kilograms per cubic metre.
- Theoretical weight
- The weight calculated from nominal dimensions and a standard density. Actual weight differs with thickness tolerance, composition and shape.
Standards and sources
- Stockholder's general data, Issue 3, 02/2011 (formulae, densities) and alloy datasheets: company publications, not standards.
- Euro Inox, Tables of Technical Properties, Vol. 5, 2nd ed. 2007: EN 10088-1 itself not read.
- BS EN 1991-1-1 and UK National Annex (floor loads): named only; not read. Confirm with a structural engineer.
Questions we are asked
How much does a square metre of 3 mm brass sheet weigh?
About 25.4 kg, using a density of 8.45 g/cm³. Sources give brass between 8.44 and 8.5, so the true figure is within about half a kilogram. Mild steel of the same size is 23.6 kg and aluminium 8.1 kg.
Is stainless steel heavier than mild steel?
Very slightly: 304 at 7.9 against 7.85 for mild steel, and 316 at 8.0. For a 3 mm sheet the difference is a few hundred grams per square metre, so for planning treat them as the same.
What is the weight of 25 x 25 x 2 mm square tube?
About 1.44 kg per metre in mild steel, from the stockholder's formula. Real tube has rounded outer corners, so the manufacturer's table gives slightly less. In stainless 304 it is about 1.45 kg per metre.
How do I turn kilograms into a floor load?
Multiply the mass by 9.81 to get newtons: 150 kg is 1.47 kN. Floor loads are then checked by an engineer against the area and the point loads the piece creates. This sheet gives no allowable floor load: those come from the design codes and the building.
Can I rely on these weights for shipping?
No. They are theoretical weights of the metal alone. Ask the partner for the packed weight of each crate, which includes the core, hardware, packaging and the crate.
Why do different tables give slightly different densities?
Because the alloy, the grade and the temper differ, and because sources round differently: brass is 8.44 in one datasheet and 8.5 in another. The difference is under 1 per cent and does not change a planning decision.
Download the factsheet
A two-page A4 PDF with the density table, bar and tube formulas and the worked examples, to keep with your project file.