Roofing Calculators
Shingles, underlayment and metal roofing, sized for waste by roof complexity. 9 free calculators.
Roofing material is sold by the "square" (100 sq ft), and how much waste to add on top of the roof's raw area depends heavily on how complex the roofline is - a simple gable wastes far less than a roof with multiple valleys and hips.
These calculators convert roof dimensions or pitch into squares, then apply a waste percentage matched to roof complexity, and list the full material set - underlayment, starter strip, ridge cap and drip edge - not just the shingles.
Last reviewed September 2026
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All 9 Roofing calculators
Roofing Material Calculator
Roofing material calculator for shingle bundles, underlayment, starter strip, ridge cap and drip edge, from footprint, pitch and edge lengths.
Roof Pitch Calculator
Roof pitch calculator that turns any rise and run measurement into the X in 12 pitch, a ratio, an angle in degrees and the roof area multiplier.
Ice & Water Shield Calculator
Ice and water shield calculator for eave and valley runs. Get the roll count and waste-adjusted area, with a 100 ft eave and 20 ft valley example.
Metal Roofing Calculator
Metal roofing calculator for panel count, total panel length and fasteners, using effective coverage width and panels cut to the slope length.
Plywood Sheathing Calculator
Plywood sheathing calculator for roof decking sheets in 4x8, 4x9 or 4x10 sizes, from footprint area, pitch and waste, with a worked example.
Gutter Calculator
Gutter calculator for gutter sections, hangers, end caps and downspouts from your gutter run and roof area, with downspout sizing and a 150 ft worked example.
Attic Ventilation Calculator
Attic ventilation calculator for the net free vent area your attic needs, split between soffit and ridge vents, with a 1,200 sq ft worked example.
Roof Truss Calculator
Roof truss calculator for truss count from roof length and 16 or 24 in. spacing, with a 30 ft worked example and a note on what it excludes.
Hip & Valley Rafter Length Calculator
Hip and valley rafter length calculator for any common rafter run and roof pitch, with the diagonal factor and a 12 ft, 6:12 worked example.