Shingle Calculator

Shingles are sold in bundles, three bundles usually cover one roofing square, and a square is one hundred square feet of finished roof. That chain of units is why a shingle order is quoted in squares rather than in bundles or in area: it is the language roofers and suppliers both use, and it hides a small amount of arithmetic that is easy to get wrong. Waste is the number that decides whether the order is right. A simple gable roof wastes the least, because most courses run unbroken from eaves to ridge. Hips, valleys, dormers, chimneys and skylights all force cuts, and the offcuts are rarely reusable. Ten per cent is a reasonable allowance for a straightforward roof; fifteen per cent or more is wiser for a complex one, and starter strips for the eaves and cap shingles for the ridges are extras on top of the field shingles. Materials beyond the shingles are easy to overlook when budgeting. Underlayment, drip edge, valley flashing, nails, and ridge and hip cap all belong in the order, and together they can add a noticeable share to the total. Underlayment in particular is measured in squares too, and its quantity generally matches the roof area with no waste, since it is laid in overlapping rolls. This calculator converts your roof area into squares and bundles, adds waste and rounds up, and estimates the ridge cap you will need along hips and ridges. It assumes three-tab or architectural shingles at the standard three bundles per square; some products differ, so check the coverage printed on the bundle before ordering.

This calculator returns estimates for planning and general information only. It is not engineering, architectural, structural, electrical or code advice, and it cannot replace a qualified professional who has seen the site. Material quantities depend on the actual dimensions, the product you buy and local building codes, so confirm the figures before ordering materials or starting work, and always follow local regulations.