About this calculator
Full shingle roof takeoff: roof area in squares, shingle bundles, underlayment, ice & water shield, starter, hip & ridge cap, drip edge and nails. Works for gable, hip and mono-pitch roofs.
How it’s calculated
True roof area = plan area including overhang × pitch factor, where pitch factor = √(1 + (rise ÷ run)²). Hip roofs with the same pitch on every side have the same area as a gable over the same footprint. Only the edges differ. Hip length = (half width) × √(2 + (rise ÷ run)²).
One square = 100 sq ft. Most shingles come 3 bundles to the square.
Worked example
With these inputs:
- Roof shape
- Gable (two slopes)
- Building length (wall to wall)
- 40 ft
- Building width (wall to wall)
- 28 ft
- Overhang (eaves and verge)
- 12 in
- Pitch entered as
- Rise per 12
- Rise per 12
- 6
- Roof covering
- Architectural shingles
- Waste allowance
- 10%
the result is:
- Roofing squares
- 15.5 squares
- Roof surface area
- 1,408.7 sq ft
- Plan area (with overhang)
- 1,260 sq ft
- Pitch factor
- × 1.118 (26.6°, 6/12)
- Eaves length
- 84 lin ft
Tips from the trade
- Valleys, dormers and chimneys add waste. Go to 15–20% on cut-up roofs.
- Measure from the eaves, never from the ground. Satellite measurements are a starting point, not a takeoff.
- Order ridge material for the hips too. It is the most commonly forgotten line.
Common questions
How many bundles of shingles per square?
Three for most architectural and 3-tab shingles. Some heavy designer shingles are 4 or 5.
How many roof tiles per m²?
About 10 for large interlocking concrete tiles, 60 for plain tiles and about 20 for 500 × 250 slates.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.