Calculate roofing materials including shingles, underlayment, and ridge caps for your roof.
This roofing calculator converts your roof footprint and pitch into the true sloped roof area, then estimates the shingles, tiles or metal sheets and underlay you need. Roofing is sold in “squares” (100 sq ft) in the US and by the m² in the UK – this tool reports both.
| Pitch | Area multiplier |
|---|---|
| 4:12 (18°) | 1.054 |
| 6:12 (27°) | 1.118 |
| 9:12 (37°) | 1.25 |
A 10 m × 6 m footprint = 60 m². At a 6:12 pitch the sloped area is 60 × 1.118 = 67 m² per plane; double it for a simple gable roof, then add 15% waste.
Most shingles come 3 bundles per square (100 sq ft). Calculate your roof area in squares and multiply by 3.
A roofing square is 100 square feet (9.29 m²). It’s the standard unit for measuring and ordering roofing materials.
Steeper pitches have more surface area. A 6:12 pitch adds about 12% more area than a flat roof; a 12:12 pitch adds about 41%.
Asphalt shingles typically last 20–30 years, concrete tiles 40 years or more, and natural slate far longer. Lifespan depends on the material, the pitch and how exposed the roof is.
Work out the footprint from the ground and multiply by a pitch factor for the slope. Our Roof Area calculator does exactly this from your plan size and pitch.
