Slate Roof Calculator — Slate Count, Nails & Battens
Calculate slate count from headlap and gauge, nail requirements (2 per slate) and battens at gauge centres.
Total roof area (both sides if pitched)
10% standard, 15%+ for complex roofs
How We Calculate This
This calculator determines the slate count from your roof area, slate size and headlap. The gauge (batten spacing) is calculated from the slate dimensions.
The formula
Gauge = (Slate length \u2212 Headlap) ÷ 2
Slates per m² = 1,000,000 ÷ (Gauge × Slate width)
Total slates = Roof area × Slates per m² × (1 + Wastage %)
Frequently Asked Questions
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Last updated: March 2026
All calculations are estimates. Verify with your supplier.