Roof Tile Calculator UK
Turn a measured sloping roof area and the exact tile manufacturer’s tiles-per-m² rate into a field-tile quantity. No assumed tile size, headlap, gauge or hidden waste percentage.
Calculate field roof tiles
Enter the actual sloping roof area, then copy the tiles per m² figure from the technical data for the exact tile and installation specification. If the rate changes with gauge/headlap, use the rate that matches the designed roof.
How the roof tile calculation works
The calculator then rounds up to a whole base tile quantity. If you enter an extra percentage, that percentage is applied to the theoretical tile quantity before the final whole-tile rounding.
Roof tiles overlap. The effective covering rate depends on the tile/system and can vary with gauge or headlap, so physical tile dimensions alone do not reliably tell you tiles per m².
Worked example
A measured roof area of 80.00 m² using a product stated at 17.7 tiles/m² gives 1,416 theoretical field tiles. At the default 0% extra allowance, that remains 1,416 whole field tiles.
Use measured roof surface area. For simple pitched geometry, start with the Roof Area Calculator.
Find the tiles-per-m² figure for the exact tile and the intended gauge/headlap or roof specification.
The calculator starts at 0%. Do not hide cuts, breakage, detailing or spares inside an unexplained universal percentage.
Why one roof-tile rate cannot fit every product
Current UK manufacturer data demonstrates the range. BMI Redland 49 states 17.7 tiles/m². Wienerberger Sandtoft Standard Pattern states 16.4 tiles/m² at 75 mm headlap and 17.9 tiles/m² at 100 mm headlap. BMI plain-tile technical data can be around 60 tiles/m². These are product/system figures, not defaults for this calculator.
Current UK manufacturer references checked for this calculator:
BMI Redland 49 — product technical data
Wienerberger Sandtoft Standard Pattern — covering capacity/headlap data
What this calculator deliberately leaves out
- Roof pitch selection and confirmation of tile suitability at that pitch.
- Headlap/gauge design—the manufacturer’s resulting tiles-per-m² rate is the input.
- Ridge, hip, valley, verge, eaves/top tiles, clips, fixings and ventilation components.
- An automatic breakage, cutting or waste percentage.
- Structural design, fixing specification and Building Regulations compliance.
Planning estimate only. Check the current manufacturer installation data and supplier quantities for the exact roofing system before ordering. A field-tile count does not constitute a full roof specification.
Continue the roofing estimate
Frequently asked questions
Where do I get the tiles-per-m² figure?
Use the current technical data for the exact tile product and the intended gauge/headlap or roof system. Do not substitute a generic roof-tile rate.
Does this calculate roof area?
No. Enter the already-established sloping roof surface area. Use the Roof Area Calculator first if you need to derive a simple pitched-roof area.
Does the result include ridge and hip tiles?
No. The result is for field tiles only. Linear fittings and special tiles depend on roof geometry and the chosen product system.
Why is the default extra allowance 0%?
Because there is no universal percentage that suits every roof, tile, cutting pattern or ordering strategy. Enter an allowance only when you have chosen one for the actual job.