Measuring a roof from the ground
You don’t need to climb onto the roof to estimate it. Measure the building’s footprint, add the overhang, and find the pitch from plans, the attic or a gable end. The roof area calculator turns those into the sloped surface area. Roofs with several pitches, dormers or levels should be split into sections and added up.
From area to bundles
Roofing is priced by the square (100 sq ft) and sold in bundles, but bundles per square vary between products. Read the wrapper or the data sheet of the exact shingle you plan to buy, and set a waste allowance that suits the roof’s hips, valleys and cuts. Starter, ridge cap, underlayment and flashing are separate items.