Steel Plate Weight Calculator
Mass per square metre, per plate and in total from size and thickness.
Quick answer
With the default inputs: Length 2000 · Width 1000 · Thickness 10 etc.Total mass 785.00 kg
Edit the inputs below to recalculate.Inputs
Result
Total mass
785.00kg
| Area per plate | 2.000m² |
| Mass per m² | 78.50kg/m² |
| Mass per plate | 157.00kg |
| Total area | 10.000m² |
| In tonnes | 0.785t |
| Plates per tonne | 6.37sheets |
| Volume per plate | 0.0200m³ |
| Both faces | 20.00m² |
Mass per square metre is thickness in mm times 7.85 — the handiest number for plate: 78.5 kg/m² at 10 mm and 157 kg/m² at 20 mm. Checker plate adds a raised pattern, usually taken as the plain thickness times 1.05-1.08.
Reverse: known result, work out one input
Enter a target result; the other inputs stay fixed and this one is worked out.
Formula
| Area | A = length (m) × width (m) |
| Mass per m² | W = thickness (mm) × 7.85 |
| Mass per plate | A × W |
| Total | per plate × quantity |
| Expanded | W = L × W × T × 7850 in metres |
| Plates per tonne | N = 1000 ÷ mass per plate |
2000 × 1000 × 10 mm, five plates: 2.000 m² each, 78.50 kg/m², 157.00 kg per plate, 785.00 kg total (0.785 t), about 6.37 plates to the tonne.
How to work it out
- Unit weight: 1 mm of steel plate is 7.85 kg/m², so weight per m² = thickness in mm × 7.85. A 10 mm plate is 78.5 kg/m².
- Weight per piece = length × width × thickness × 7.85 ÷ 10⁹ with dimensions in mm, or simply area × unit weight.
- Multiply by the count for the total. Checker plate adds 2.5-3 kg/m² for the pattern.
- Divide by 1000 for tonnes. When buying by piece, remember plates carry length and width tolerances.
- For cut or holed plates add 5-10% waste; the cutting method (plasma or shear) sets the offcut width.
Where it goes wrong
- Mixing up 7.85 g/cm³ and 7850 kg/m³ — they are the same density, but mixed units produce results out by a factor of a thousand or ten thousand. This is the commonest calculation accident in the trade.
- Ignoring minus thickness tolerance — hot-rolled plate runs 3-7% light in practice, so a nominal 10 mm plate may measure 9.3-9.7 mm and theoretical weight overstates the delivery.
- Costing checker plate as flat — the pattern is 0.5-1.5 mm high and adds 2.5-3 kg/m², so 5 mm checker behaves like 7.5-8 mm flat.
- Using one density for every metal — stainless is 7.93, aluminium 2.7, copper 8.9; applying 7.85 to all is out by a factor.
Material and cost
Q235B plate 3800-4500 CNY/t, Q355B 4200-5000, stainless 304 18000-26000, aluminium 20000-26000. Cutting 3-15 CNY/m or 200-600 CNY/t.
On site
- Decoiled plate is 100-300 CNY/t cheaper than as-rolled but carries residual stress and poorer flatness; structural members should use as-rolled.
- Agree in the contract whether settlement is by weighbridge or by theoretical weight, since the gap is 3-7%.
- Plate over 40 mm in welded tension needs through-thickness quality — specify Z15, Z25 or Z35.
Basis
- GB/T 709-2019 Dimensions, shapes, mass and tolerances of hot-rolled steel plate and strip
- GB/T 3274-2017 Hot-rolled thick steel plate and strip
- GB/T 708-2019 Dimensions, shapes, mass and tolerances of cold-rolled steel plate and strip
FAQ
Why does theoretical plate mass not match the scales?
Because the standard permits negative thickness tolerance — a 10 mm plate may be 9.2 mm, giving 72.2 kg/m² instead of 78.5, an 8% shortfall. Mills deliver on theoretical weight by trade custom, so the calculated total running high is expected; a deviation beyond tolerance means undersized plate, so check with a caliper on delivery.
How do I handle grating and checker plate?
Grating is not area times thickness — makers publish mass per square metre by specification (30 × 3 flat bar at 30 mm pitch is about 30 kg/m²), so use the table. Checker plate is the plain thickness times 1.05-1.08, the pattern being 0.5-1.0 mm high, which barely matters on large plates.
Why is thin sheet more penalised by theoretical weight?
Because tolerance is proportional: a 1 mm sheet permits ±0.1 mm, a 10% band, worse than the 8% on 10 mm plate. Thin sheet also covers more area per tonne, so errors accumulate. Colour-coated sheet at 0.5 mm should be 3.93 kg/m² but often measures 3.5 — the origin of the “thinner every year” complaint.
Cite this page
Use this format in reports, method statements or coursework. The link is permanent.
Building Calculator. Steel Plate Weight Calculator. 2026-10-25. https://jianzhujisuan.com/en/steel-plate-weight
Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.