Zinc Consumption Calculator
Estimate how many kilograms of zinc a galvanizing job consumes per tonne of steel — the coating that stays on the steel plus dross and ash losses. Zinc is the single biggest variable cost in HDG.
Advanced — dross & ash allowance
- Coating mass 607 g/m²
- Surface area 65 m²/t
- Coating zinc 39 kg/t
- Dross & ash 12 kg/t
How zinc consumption is calculated
Galvanizing coats surface, but steel is bought and sold by weight. So zinc consumption per tonne is the coating mass per square metre multiplied by how much surface area a tonne of that steel has — then a margin for dross and ash:
Coating mass is about 7.14 g/m² per micron of zinc (zinc density 7.14 g/cm³). Surface area per tonne is the variable that dominates: a tonne of thin, complex fabrication has far more area than a tonne of heavy plate, so it consumes much more zinc.
Worked example
A 3–6 mm structural job to an 85 µm (ASTM A123) coating, 30% dross/ash allowance:
- Coating mass = 7.14 × 85 = 607 g/m²
- Surface area ≈ 65 m²/t (typical for 3–6 mm fabrication)
- Coating zinc = 607 × 65 ÷ 1000 ≈ 39 kg/t
- Dross & ash = 39 × 30% ≈ 12 kg/t
- Total zinc consumption ≈ 51 kg/t (≈ 5.1% of steel mass)
Tracking this against actual zinc purchased is one of the most important plant KPIs — see Zinc Consumption KPIs, and cost it with the Galvanizing Cost Calculator.
Manage zinc across the plant
- Cost zinc into price per tonne (Service Cost Calculator)
- Size the zinc bath inventory (Plant Design)
- Track dross & ash as efficiency KPIs
- Downloadable reports to share with management
Questions
How much zinc per tonne of steel?
Typically 38–70 kg/t (≈ 4–7% of steel mass) — the coating on the steel plus dross and ash. Thin, complex sections consume more because they have more surface area per tonne.
How is coating mass related to thickness?
About 7.14 g/m² per micron. An 85 µm coating (ASTM A123) ≈ 607 g/m².
What is dross and ash allowance?
Not all zinc ends up on the steel — dross (zinc-iron) settles to the kettle floor and ash forms on the surface. Total consumption is usually 25–40% above the coating that stays on the work.
Is this calculator free?
Yes — no sign-up. The members tools cost zinc into price per tonne and size bath inventory across the plant.