Plate weight in kg per square metre is the thickness in mm times 7.85. A 10 mm plate weighs 78.5 kg/m². For a plate of any size, weight = length (m) × width (m) × thickness (mm) × 7.85. A 2500 × 1250 mm sheet of 10 mm plate weighs 245.3 kg.
The formula
One square metre of steel plate that is 1 mm thick has a volume of 0.001 m³, and at 7850 kg/m³ it weighs 7.85 kg. So the weight scales directly with thickness:
kg per m² = thickness (mm) × 7.85Weight (kg) = length (m) × width (m) × thickness (mm) × 7.85
For a size given in millimetres on all sides, use length (mm) × width (mm) × thickness (mm) × 0.00000785.
Plate weight chart
The last two columns give the weight of one whole sheet in two common sizes, 2500 × 1250 mm and a nominal 8 ft by 4 ft sheet of 2440 × 1220 mm. Check the exact sheet size with your supplier, since mills and traders list slightly different sizes.
| Thickness | kg per m² | kg per ft² | kg per 2500 × 1250 sheet | kg per 2440 × 1220 sheet |
|---|---|---|---|---|
| 1 mm | 7.85 | 0.729 | 24.5 | 23.4 |
| 1.2 mm | 9.42 | 0.875 | 29.4 | 28.0 |
| 1.6 mm | 12.56 | 1.167 | 39.2 | 37.4 |
| 2 mm | 15.70 | 1.459 | 49.1 | 46.7 |
| 2.5 mm | 19.62 | 1.823 | 61.3 | 58.4 |
| 3 mm | 23.55 | 2.188 | 73.6 | 70.1 |
| 4 mm | 31.40 | 2.917 | 98.1 | 93.5 |
| 5 mm | 39.25 | 3.646 | 122.7 | 116.8 |
| 6 mm | 47.10 | 4.376 | 147.2 | 140.2 |
| 8 mm | 62.80 | 5.834 | 196.2 | 186.9 |
| 10 mm | 78.50 | 7.293 | 245.3 | 233.7 |
| 12 mm | 94.20 | 8.751 | 294.4 | 280.4 |
| 16 mm | 125.60 | 11.669 | 392.5 | 373.9 |
| 20 mm | 157.00 | 14.586 | 490.6 | 467.4 |
| 25 mm | 196.25 | 18.232 | 613.3 | 584.2 |
| 32 mm | 251.20 | 23.337 | 785.0 | 747.8 |
| 40 mm | 314.00 | 29.172 | 981.2 | 934.7 |
| 50 mm | 392.50 | 36.464 | 1,226.6 | 1,168.4 |
Sheet metal gauges (SWG)
Thin sheet is often ordered by gauge, not thickness. The standard wire gauge numbers below correspond to these thicknesses. A higher gauge number means thinner sheet. Gauge systems differ, so make sure your supplier means SWG.
| Gauge | Thickness | kg per m² |
|---|---|---|
| 10 SWG | 3.25 mm | 25.52 |
| 12 SWG | 2.64 mm | 20.74 |
| 14 SWG | 2.03 mm | 15.95 |
| 16 SWG | 1.63 mm | 12.76 |
| 18 SWG | 1.22 mm | 9.57 |
| 20 SWG | 0.91 mm | 7.17 |
Worked example: weight and price of a plate
A base plate is cut from 12 mm plate, 400 mm × 400 mm, and you need 8 of them.
- Weight of one plate = 0.4 × 0.4 × 12 × 7.85 = 15.07 kg.
- Eight plates = 120.6 kg.
- At an example rate of ₹75 per kg, that is ₹9,043.
A full sheet works the same way. A 2500 × 1250 mm sheet of 10 mm plate weighs 78.5 × 3.125 = 245.3 kg, which at ₹75 per kg is about ₹18,398. The material cost of cutting plates out of a sheet is based on the whole sheet, not only the plates, because the offcuts are part of what you buy. For converting rates between per tonne, per kg and per square metre, see the rate conversion guide.
Slips to avoid
- Mixing mm and m. The 7.85 factor works with thickness in mm and area in m². If every side is in mm, use 0.00000785.
- Pricing only the plates, not the sheet. Offcuts and kerf are paid for.
- Treating chequered plate like flat plate. The raised pattern adds weight, so use the supplier table for it.
- Forgetting tolerance. Plate thickness varies a little, and delivered weight can differ from theoretical.
For bars and flats there is a matching bar weight chart, and the guide to weight and cost covers the whole estimate. Steel Table India also takes custom flat sizes, so a narrow plate can be entered as a flat and priced at your own rate.
Questions people ask
How do I calculate the weight of a steel plate?
Multiply length in m, width in m and thickness in mm, then multiply by 7.85. A 1 m by 1 m plate of 10 mm weighs 78.5 kg.
What is the weight of a 10 mm MS plate per square metre?
78.5 kg per square metre, which is 7.29 kg per square foot.
How much does an 8 by 4 feet MS sheet weigh?
For a 2440 × 1220 mm sheet, multiply the kg per square metre by 2.977. A 10 mm sheet weighs about 233.7 kg and a 3 mm sheet about 70.1 kg.
What is the density of mild steel used for plate weight?
7850 kg per cubic metre, which is why 1 mm of thickness gives 7.85 kg per square metre.
Is SWG the same as thickness in mm?
No. SWG is a gauge number, and a higher number is thinner. For example 10 SWG is about 3.25 mm and 18 SWG is about 1.22 mm.
Keep reading
Weight and cost in a few taps
Steel Table India prices flats and plates of your own size at your own rate. Free on Google Play.
For reference, not for sign-off. The weights here are theoretical values worked at 7850 kg/m³. Rolled and drawn products have tolerances, so delivered weight can differ slightly, and supplier tables govern an order. Rates are examples only. Check critical values against the relevant Bureau of Indian Standards publication and your supplier.