Steel weights
Steel plate or flat bar weight
- where
- volume of one piece (m³)
- length (mm)
- width (mm)
- thickness (mm)
- weight of one piece (kg)
- steel density (kg/m³)
- total weight (kg)
- number of pieces
Explain this equation
Works out the weight of steel plate or flat bar from its dimensions. Use it for ordering, pricing by weight, and planning lifts.
Each dimension is divided by 1000 to turn millimetres into metres, so their product is the volume in cubic metres. Steel weighs about 7850 kg per cubic metre, so volume times density gives the weight of one piece, and times the number of pieces gives the total. The calculator also gives weight per square metre, which is simply thickness in mm times 7.85.
Mass equals volume times density.
Sense check: an 8 × 4 ft sheet (2400 × 1200 mm) of 10 mm plate is about 226 kg; every millimetre of thickness adds 7.85 kg per m².
Watch out: stainless steel and aluminium have different densities (about 7900 to 8000 and 2700 kg/m³). Change ρ to suit.
Weight of a rectangular steel plate or length of flat bar from its dimensions, for ordering, lifting and pricing.
Enter your values to see the result.
Good to know
Steel density is taken as 7850 kg/m³, the value the British and European product standards use to calculate nominal masses (7.85 kg/dm³). A quick check: 1 mm thick steel weighs 7.85 kg per m², so 10 mm plate is 78.5 kg/m². For stainless steel use about 7900–8000 kg/m³ and for aluminium about 2700 kg/m³ (change the density).
Common mistake
Mixing millimetres and metres. A 2.4 m × 1.2 m × 10 mm sheet is 226 kg, not 22.6 or 2,260. Also remember that rolling tolerances mean real plate can be a few per cent heavier than nominal.
Limits
Nominal mass from nominal dimensions. Does not deduct holes, cut-outs or chamfers. Plate thickness tolerances (BS EN 10029) make actual weight vary.
Sources
- BS EN 10219-2:2019 Cold formed welded steel structural hollow sections – Part 2: Tolerances, dimensions and sectional properties (mass from density 7.85 kg/dm³; corner radius rules and area formula)
- BS EN 10365:2017 Hot rolled steel channels, I and H sections – Dimensions and masses (density 7850 kg/m³)
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the welding procedure specification (WPS), BS EN ISO 15614/9606, BS EN 1090, BS EN 1993 and manufacturers’ data. Structural welds need qualified welders and engineered designs.