GI Coil Weight Calculator
Galvanized (GI/GP) coil is carbon steel with a zinc coating, so its effective density is essentially the same as mild steel - 7.85 g/cm³. The zinc layer (typically 120–275 GSM) adds well under 1% to the weight, which this calculator treats as included.
This is an interactive calculator; enable JavaScript to use it. Enter coil OD, ID and width to get weight in kg/tonnes, plus strip length if thickness is given.
Typical GI Coil Specifications
| Density | 7.85 g/cm³ (zinc coating included) |
| Common thickness | 0.25–3mm |
| Common coil ID | 508mm or 610mm |
| Typical coil weight | 4–15 tonnes |
Example: a GI coil with 1350mm OD, 508mm ID and 1220mm width weighs about π/4 × (1350² − 508²) × 1220 × 7.85 × 10⁻⁶ ≈ 11.8 tonnes.
Coil Weight Formula
Weight (kg) = π/4 × (OD² − ID²) × Width × Density × 10⁻⁶ - with OD, ID and Width in millimetres and density in g/cm³.
Frequently Asked Questions
Does the zinc coating change GI coil weight calculations?
Not meaningfully. Zinc coating of 120–275 GSM adds less than 1% to total weight, well within normal coil tolerance, so using steel's 7.85 g/cm³ density gives accurate results.
Why do GI coils need careful handling equipment?
The zinc layer can flake or scratch if handled roughly. Decoilers and slitting lines for GI use controlled tension and appropriate knife clearances to preserve coating integrity, not different weight ratings.