A square metre of steel plate 1 mm thick weighs 7.85 kg, which is the density of steel written in convenient units. The rest is multiplication: sheet mass equals 7.85 × thickness × width × length, with thickness in millimetres and width and length in metres. A 1 500×6 000 plate 10 mm thick is 78.5 kg/m² × 9 m² = 706.5 kg; a 1 250×2 500 sheet 2 mm thick is 15.7 × 3.125 = 49.1 kg.
Formula
m = 7.85 · t · B · L
m is the sheet mass in kg, t the thickness in mm, B and L the width and length in m.
| t, mm | Mass, kg/m² | Sheet 1 500×6 000, kg | Sheet 1 250×2 500, kg |
|---|---|---|---|
| 0.5 | Mass, kg/m²3.92 | Sheet 1 500×6 000, kg35.3 | Sheet 1 250×2 500, kg12.3 |
| 0.8 | Mass, kg/m²6.28 | Sheet 1 500×6 000, kg56.5 | Sheet 1 250×2 500, kg19.6 |
| 1 | Mass, kg/m²7.85 | Sheet 1 500×6 000, kg70.6 | Sheet 1 250×2 500, kg24.5 |
| 1.5 | Mass, kg/m²11.8 | Sheet 1 500×6 000, kg106.0 | Sheet 1 250×2 500, kg36.8 |
| 2 | Mass, kg/m²15.7 | Sheet 1 500×6 000, kg141.3 | Sheet 1 250×2 500, kg49.1 |
| 3 | Mass, kg/m²23.5 | Sheet 1 500×6 000, kg211.9 | Sheet 1 250×2 500, kg73.6 |
| 4 | Mass, kg/m²31.4 | Sheet 1 500×6 000, kg282.6 | Sheet 1 250×2 500, kg98.1 |
| 5 | Mass, kg/m²39.3 | Sheet 1 500×6 000, kg353.3 | Sheet 1 250×2 500, kg122.7 |
| 6 | Mass, kg/m²47.1 | Sheet 1 500×6 000, kg423.9 | Sheet 1 250×2 500, kg147.2 |
| 8 | Mass, kg/m²62.8 | Sheet 1 500×6 000, kg565.2 | Sheet 1 250×2 500, kg196.3 |
| 10 | Mass, kg/m²78.5 | Sheet 1 500×6 000, kg706.5 | Sheet 1 250×2 500, kg245.3 |
| 12 | Mass, kg/m²94.2 | Sheet 1 500×6 000, kg847.8 | Sheet 1 250×2 500, kg294.4 |
| 16 | Mass, kg/m²125.6 | Sheet 1 500×6 000, kg1 130 | Sheet 1 250×2 500, kg392.5 |
| 20 | Mass, kg/m²157.0 | Sheet 1 500×6 000, kg1 413 | Sheet 1 250×2 500, kg490.6 |
| 25 | Mass, kg/m²196.3 | Sheet 1 500×6 000, kg1 766 | Sheet 1 250×2 500, kg613.3 |
| 30 | Mass, kg/m²235.5 | Sheet 1 500×6 000, kg2 120 | Sheet 1 250×2 500, kg735.9 |
| 40 | Mass, kg/m²314.0 | Sheet 1 500×6 000, kg2 826 | Sheet 1 250×2 500, kg981.3 |
The 1 500×6 000 format is hot-rolled plate to GOST 19903 and GB/T 709, the 1 250×2 500 format is cold-rolled and galvanised sheet to GOST 19904 and GB/T 708. Thin sheet up to 3 mm is rarely shipped in 1 500×6 000: it travels as coil and is cut on site.
Coil: the running metre of strip
A coil is a strip wound into a spiral, and it is easier to count from the running metre: the mass of a metre of strip equals 7.85 × thickness × width in millimetres divided by a thousand. A 1 250 mm strip 1 mm thick is 9.81 kg/m; a 1 500 mm strip 3 mm thick is 35.3 kg/m. Knowing the coil mass from the tag, the strip length is obtained by division: a 12 t coil of 1 250×1 strip is 1 223 m. The roll-former and the cutting line need exactly this figure.
| Width, mm | t, mm | Mass of 1 m of strip, kg | Metres of strip per tonne |
|---|---|---|---|
| 1 000 | t, mm0.5 | Mass of 1 m of strip, kg3.92 | Metres of strip per tonne254.8 |
| 1 000 | t, mm1 | Mass of 1 m of strip, kg7.85 | Metres of strip per tonne127.4 |
| 1 000 | t, mm2 | Mass of 1 m of strip, kg15.7 | Metres of strip per tonne63.7 |
| 1 000 | t, mm3 | Mass of 1 m of strip, kg23.6 | Metres of strip per tonne42.5 |
| 1 250 | t, mm0.5 | Mass of 1 m of strip, kg4.91 | Metres of strip per tonne203.8 |
| 1 250 | t, mm1 | Mass of 1 m of strip, kg9.81 | Metres of strip per tonne101.9 |
| 1 250 | t, mm2 | Mass of 1 m of strip, kg19.6 | Metres of strip per tonne51.0 |
| 1 250 | t, mm3 | Mass of 1 m of strip, kg29.4 | Metres of strip per tonne34.0 |
| 1 500 | t, mm1 | Mass of 1 m of strip, kg11.8 | Metres of strip per tonne84.9 |
| 1 500 | t, mm2 | Mass of 1 m of strip, kg23.6 | Metres of strip per tonne42.5 |
| 1 500 | t, mm3 | Mass of 1 m of strip, kg35.3 | Metres of strip per tonne28.3 |
| 1 500 | t, mm5 | Mass of 1 m of strip, kg58.9 | Metres of strip per tonne17.0 |
Coil: from two diameters
When there is no tag and the coil stands in the warehouse, the mass comes from geometry: the volume of the ring multiplied by density. The inside diameter is set by the uncoiler: hot-rolled coils usually 762 mm, cold-rolled and galvanised 508 or 610 mm. A 1 500 mm coil with an outside diameter of 1 800 mm on a 762 mm eye is 24.6 t; a 1 250 mm coil at 1 500 and 610 mm is 14.5 t; a 1 000 mm coil at 1 200 and 508 mm is 7.3 t. The limit on the mass of one coil is set not by the mill but by the customer’s crane and uncoiler, so the maximum coil mass is written into the specification.
Formula
M = π/4 · (D² − d²) · b · 7.85 / 10⁶
M is the coil mass in kg; D and d are the outside and inside diameters, b the width, all in mm.
Thickness tolerance and mass
All the tables above are at nominal thickness. The dimension standards set a tolerance on thickness: GOST 19903 and GOST 19904 by precision class, GB/T 709 and GB/T 708 by deviation category. A 10 mm plate rolled at the lower limit of the tolerance weighs less than nominal, and with shipment by theoretical weight the buyer pays for steel that is not there. That is why the specification to the mill records three things: the thickness tolerance category, the shipment basis, actual or theoretical weight, and the right of the bureau’s inspector to measure the thickness with a micrometer before loading. The actual mass of the batch is by scale and mill certificate.
Theoretical weight at a steel density of 7.85 g/cm³, calculated by the same function as the catalogue tables and the calculator. The actual weight of the batch is by scale and mill certificate.
