Roof Shingle Calculator
Calculate roofing squares, bundles of shingles, starter strips and ridge cap for any roof area.
The roof shingle calculator returns bundles, squares, starter strips and ridge cap for any roof. Roofing is sold by the square - 100 square feet of coverage - and most shingles come 3 bundles per square (premium designer shingles come 4). Enter the roof area directly if you have it from a takeoff or quote, or enter the building footprint plus pitch and the calculator multiplies by the pitch factor (sqrt((rise/12)^2 + 1)) to get the actual sloped roof area. Add 10% waste for a simple gable, 15% for hip roofs with valleys and 20% for complex roofs with dormers, skylights and multiple penetrations.
Explore all our roofing calculator tools, or browse the full construction & home improvement diy calculators.
Frequently asked questions
Most asphalt shingles (3-tab and architectural) come 3 bundles per square (100 sq ft). For a 2000 sq ft roof with 10% waste = 2200 sq ft = 22 squares = 66 bundles. Premium designer shingles come 4 bundles per square (88 bundles for the same roof). Always add starter strip bundles (1 per ~100 ft of eaves) and ridge cap bundles (1 per ~20 ft of ridge).
1 roofing square = 100 square feet of roof surface area. The unit comes from the bundle math: most shingles are sized so that 3 bundles cover exactly 1 square (100 sq ft). Roofers quote everything in squares, and ordering shingles is faster in squares than square feet. A 2,400 sq ft roof = 24 squares.
Multiply the footprint by the pitch factor: sqrt((rise/12)^2 + 1). For a 6/12 pitch: sqrt(0.25 + 1) = 1.118. So a 40x30 ft footprint with a 6/12 gable roof has 40 x 30 x 1.118 = 1,342 sq ft of roof. Steeper roofs have bigger multipliers - 12/12 (45 degrees) is 1.414. Use the roof pitch calculator if you do not know the pitch.
10% for simple gable roofs with no valleys or dormers. 15% for hip roofs (more cuts at the hips). 20% for complex roofs with dormers, skylights, multiple ridges, valleys and any roof with lots of penetrations. Steep roofs over 10/12 also bump waste up because installation is slower and pieces get dropped.
Ice and water shield is required by code along eaves in cold climates (typically the first 6 ft up from the eaves) and around valleys, chimneys and skylights everywhere. The rest of the roof gets felt or synthetic underlayment. In warm climates, code may only require underlayment without ice shield. The roofing underlayment calculator handles both.