TMT, tubes, roofing, cement & blocks
How steel weight is calculated
Grades, sizes and the unit each material is priced in.
Answer
How is steel weight calculated?
Explanation
The formulas
TMT round bar: d² ÷ 162.2 kg per metre, where d is the nominal diameter in mm. The 162.2 comes from the circular area and 7850 kg/m³.
Square tube: (A² − (A − 2t)²) × L × 7850.
Rectangular tube: (A×B − (A−2t)(B−2t)) × L × 7850.
Round pipe: π × (OD − t) × t × L × 7850.
Flat and plate: width × thickness × length × 7850.
Detail
Why we calculate rather than look up
Published standard-weight tables vary by manufacturer and by the tolerance assumed. A site that quietly looks up a table gives you a confident number you cannot check, and if the table does not match your supplier the number is wrong.
Calculating from geometry with a stated density means the arithmetic is visible. If you disagree with it, you can see exactly where.
Detail
Why actual weight differs
Nominal dimensions are not exact dimensions. Rolling tolerance means a bar or section can be slightly heavier or lighter than the calculation suggests, and mill certificates state the tolerance that applies.
That is why these figures are for estimation and quotation preparation, and why material is weighed at supply.
Questions
Also asked
Why does my supplier quote a different weight per metre?
Usually a different assumed tolerance or a different table. Compare the formula and the density rather than the totals — the difference is always in one of those.
Is the theoretical calculated weight what I will be billed?
No. It is a theoretical figure from entered geometry and nominal density. Actual supplied weight can vary within manufacturing tolerances and according to the commercial measurement basis used. Commercial quantity and billing basis are confirmed on the quotation.
Next
Ready to specify it?
Calculate the weight, add the lines and send one structured quotation request.