Roofing calculator
Measure the footprint of the house and the roof pitch to estimate the actual roof area, roofing squares, shingle bundles or tiles to order.
Your estimate
Roof surface area
116 m²
- Area to order (incl. extra)
- 128 m²
- Footprint incl. overhang
- 95 m²
- Pitch (degrees)
- 35
- Pitch (rise in 12)
- 8.4
- Pitch (percent)
- 70 %
- Roof tiles
- 1,277
Estimates for planning only — not a quote, survey or financial advice.
How this is calculated
Formula
- Footprint = (length + 2 × overhang) × (width + 2 × overhang)
- Roof area = footprint ÷ cos(pitch) — the pitch factor
- Pitch: rise in 12 = tan(angle) × 12 · percent = tan(angle) × 100
- Squares = area to order ÷ 100 ft² · bundles = squares × bundles per square · tiles = area × tiles per m²
Assumptions
- The footprint method is exact for gable and hip roofs where every slope has the same pitch. Dormers, valleys, different pitches and towers need to be measured separately.
- Most asphalt shingles come 3 bundles to a square, but check the wrapper — some heavier shingles need more.
- Tiles per m² depend on the tile: large interlocking tiles are roughly 10 per m², small plain tiles roughly 60. Use the manufacturer's figure.
- Working on roofs is dangerous. For structural changes or new roof structures, ask a qualified roofer or structural engineer.