Reviewed, sourced guidance
Estimate roof tiles and whole packs
Direct answer
Multiply sloped area by the exact product’s tiles-per-square-metre rate. Apply any entered waste allowance to that calculated quantity, then round up once to whole tiles and again to whole packs.
A useful tile estimate shows the net count, any entered allowance and the pack rounding separately.
Key takeaways
- Start with sloped area, not floor plan area.
- Use the manufacturer rate for the selected product.
- Show waste and pack rounding as separate steps.
- Keep spare tiles and special units outside the field-tile total.
Show the rounding
Calculate the net quantity from sloped area and the selected product rate. Apply the entered waste percentage to that calculated quantity before rounding up to a whole tile; round the resulting order quantity up again to the merchant’s pack size.
Pack count is the entered order quantity divided by the merchant’s number of tiles per pack, rounded up.
- Net tiles = ceiling of area × product coverage.
- Order tiles = ceiling of net tiles × (1 + allowance).
- Packs = ceiling of order tiles ÷ tiles per pack.
Sources for this section: Cushty, Roof Tile Calculator UK (observed 2026-09-25)
Keep accessories out of the field count
A tile calculator can estimate field units while leaving special pieces uncounted. That boundary must stay visible beside the result.
Ridge, hip, verge, valley, eaves and ventilation components should be checked as separate line items.
- Confirm pack size with the current merchant listing.
- Check colour, batch, finish and delivery quantity before payment.
- Keep a copy of the product data used for the calculation.
Sources for this section: Cushty, Roof Tile Calculator UK (observed 2026-09-25)Marley, Duo Modern product data (observed 2026-09-25)
Next steps
- Confirm the pack size and any special tile counts.
- Use the quote checklist before approving an order.