Roofing Calculators
Shingle, pitch, material, and ventilation calculators
Shingle Calculator
Calculate bundles, squares, and waste for an asphalt shingle roof replacement.
OpenRoof Pitch Calculator
Convert roof pitch between ratio (X:12), degrees, and percent slope, with pitch multiplier and slope category.
OpenPolyiso R-Value Calculator
Convert polyiso insulation thickness to R-value and back, with LTTR design values, cold-weather drift, suggested layer build-ups, and board feet.
OpenAttic Ventilation Calculator
Size attic ventilation by Net Free Area using the IRC 1/150 and 1/300 rules, balance intake and exhaust, and convert to linear feet of ridge and soffit vent.
OpenRoofing Cost Calculator
Estimate roofing cost per square by material, pitch, tear-off, complexity, and region — a transparent 2026 cost range with no signup and no address.
OpenRoof Replacement Cost Calculator
Estimate the full cost to replace a roof — tear-off, disposal, new material, labor, accessories, and permit — as one transparent 2026 project range.
OpenMetal Roofing Calculator
Calculate metal roof panels, screws or standing-seam clips, and eave, rake, ridge, and hip trim from roof area and linear dimensions.
OpenGutter Calculator
Size gutters and downspouts by roof area, pitch, and rainfall intensity using the SMACNA method, plus a gutter, downspout, and hanger material takeoff.
OpenUnderlayment Calculator
Calculate rolls of roof underlayment (synthetic or felt) plus ice & water shield for eaves and valleys, using the IRC 24-inch-inside-wall ice-barrier rule.
OpenDrip Edge & Ridge Cap Calculator
Calculate drip edge linear feet and pieces for eaves and rakes, plus hip & ridge cap bundles, from your roof edge measurements (IRC R905.2.8.5).
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