Roof Calculator

You can measure roof pitch by placing a level horizontally against the roof, marking 12 inches, then measuring vertically from that point to the roof surface. The vertical measurement in inches gives you the rise in the pitch (expressed as X/12). Alternatively, you can measure from inside the attic by placing a level against a rafter and measuring as described.

A roofing square is a unit of measurement specific to the roofing industry. One roofing square equals 100 square feet (9.29 square meters) of roof area. Contractors typically provide quotes and sell materials by the square rather than by square foot.

For standard asphalt shingles, you typically need 3 bundles to cover one roofing square (100 sq. ft.). However, this can vary by manufacturer and shingle type. Architectural or premium shingles might require 4-5 bundles per square due to their thicker construction.

Roof overhangs extend beyond the exterior walls of your house and require additional roofing material. Including overhangs in your calculations ensures you order enough materials to cover the entire roof surface. Overhangs are important for directing water away from your home's foundation and providing shade.

For safety reasons, it's often better to measure from the ground unless you have proper safety equipment and experience. Ground measurements can be reasonably accurate if you measure the building perimeter and account for the roof pitch. For more complex roofs, professional measurement services or drone photography can provide accurate measurements without requiring roof access.