Roofing

The roofing calculator estimates the roof area and the number of tiles or sheets you need to cover a pitched roof. Enter the roof length, width and pitch to get the total surface area and the tile count.

Common use cases

• Pitched roof replacements
• New build and extension roofs
• Garden shed and carport roofs
• Re-roofing planning and budgeting

How to use this calculator

1. Enter the roof length and width (plan view).
2. Enter the roof pitch (degrees) and tile size.
3. Press Calculate to see the actual roof surface area.
4. Use the tile count to plan your order with waste.

Example calculation

A 10 m × 6 m roof at 30° pitch has a real surface of about 69.3 m². With 42 × 33 cm tiles (≈10 per m²) you need around 693 tiles plus 10% for cuts.

Frequently asked questions

How do I calculate roof area from the floor plan?

Multiply the plan area by 1 / cos(pitch). At 30° pitch, multiply by about 1.155.

How many roof tiles per square metre?

Between 10 and 16 tiles per m² for standard concrete tiles, depending on the tile size and overlap.

How much waste should I add for roofing?

Add 10% for simple pitched roofs and 15% for hipped or complex roofs with many cuts.

Does this work for flat roofs?

For flat roofs set the pitch to 0°; the area equals the plan area.