Roof Shingle Calculator

With this roof shingle calculator's help, you will be able to quickly estimate how many bundles of shingles you need for your roof.

Roofing squares14.7581,341.64 sq ft of roof plus 10% waste

Bundles to buy453 bundles to the square

Sloped roof area1,341.64 sq ft1,200 sq ft footprint × 1.11803

Pitch multiplier1.1180346 in 12, 26.57°

Underlayment4 rolls400 sq ft rolls, with 10% for laps

Starter strip80 ftalong both eaves

Drip edge147.08 fteaves and both rake edges

Roofing nails4,723about 320 per square at four per shingle

Ridge cap40 ft2 bundles at about 33 ft each

Roof weight3,690 lbarchitectural shingles run about 250 lb per square

The method

squares = sloped roof area ÷ 100 sq ft, plus waste

A square is 100 square feet

Roofing has been sold by the square for a century, and it means exactly 100 square feet of finished roof. Three bundles make a square for most three-tab and architectural shingles, though heavier products take four or five.

Measure the footprint and multiply by the pitch multiplier rather than trying to measure the slope from the ground. For a 6 in 12 roof over a 30 × 40 foot building that is 1,342 square feet, or about 13.4 squares before waste.

Ten per cent waste suits a simple gable. A roof with hips, valleys and dormers can easily need 15–20%, because every valley means cutting shingles at an angle.