Steel weight formulas.
Practical theoretical kilogram calculations using millimetre dimensions.
Density: A practical value of 7.85 g/cm³ is used for carbon and alloy steels. Results are theoretical; actual scale weight may vary with production tolerance.
Round steel bar
Kg = π / 4 × diameter² × length × quantity × 7.85 / 1,000,000
Example: Ø75 × 3000 mm, 1 piece ≈ 104.04 kg.
Square steel
Kg = side × side × length × quantity × 7.85 / 1,000,000
Flat / rectangular steel
Kg = width × thickness × length × quantity × 7.85 / 1,000,000
Hexagonal steel
Kg = 0.866025 × across-flats² × length × quantity × 7.85 / 1,000,000
Steel tube
Kg = π / 4 × (outer diameter² − inner diameter²) × length × quantity × 7.85 / 1,000,000
Cut-size note
For cut cold-finished material, add 4 mm to diameter for TCT circular or band-saw calculations. For cut hot-rolled material, add 1 mm to thickness before entering the measurement.
Rounding method
When each row is rounded up separately, the rounded grand total is the sum of those row values.
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