Roof Tile Quantity Calculator
Estimate how many roofing tiles a sloped roof needs using actual roof area, manufacturer coverage, roof pitch and a visible cutting allowance.
Roof and tile inputs
Roof tile requirement
How roof tile quantity is calculated
The horizontal roof footprint understates the actual surface of a pitched roof. The calculator converts the plan area into sloped area, then applies the tile manufacturer's coverage rate.
Surface factor = 1 ÷ cos(pitch)
Sloped area = plan area × surface factor
Tile minimum = sloped area × tiles per m²
Order quantity = ceiling(tile minimum × (1 + waste))
Why pitch matters
At greater pitch, each horizontal metre corresponds to a longer roof surface. A tile estimate that ignores slope can therefore understate material.
Worked example
A 12 × 8 m roof has a 96 m² plan area. At a 25° pitch, its sloped surface is larger than 96 m². Applying 10.5 tiles/m² and then 7% allowance produces the practical tile order estimate shown by the calculator.
Special tiles and accessories
Ridge, hip, verge and other special pieces are often not captured by a simple tiles-per-square-metre rate. Keeping them separate makes the takeoff easier to review.
Limitations
This is a planning estimate. It does not model every roof plane, valley, dormer, cut or tile-laying bond. Final procurement should follow the roof drawing and tile manufacturer's installation data.
Frequently Asked Questions
Can I use manufacturer tiles-per-metre data?
Yes. That is the preferred input.
Does roof pitch change the tile count?
It can because it changes physical roof area.
Should waste be included?
A project-specific allowance is useful.
Are ridge tiles included?
Only if you enter them separately.