Why pitch changes everything
A roof square is 100 square feet of sloped surface. A 9/12 roof — common on older Massachusetts Colonials — has about 25% more surface than its flat footprint, and a 12/12 Cape roof about 41% more. If an estimate seems to price the footprint rather than the slope, the shortfall can be large.
Waste and accessories
Waste covers cutting at hips, valleys, dormers and rakes. A plain gable might need 10%; a cut-up Victorian with turrets and dormers can run 18% or more. Separate line items usually cover starter, ridge cap, drip edge and — important in this climate — ice and water shield along the eaves and in valleys.
Steep and high roofs
Estimating programs typically add steep charges from about 7/12 or 8/12 and high-roof charges for two stories and up. Triple-deckers and tall Victorians often qualify for both. Compare your result with the carrier’s numbers, then see our roof and hail claim appraisal page if the gap is significant.
About this converter
Is the carrier’s satellite measurement reliable?
Aerial reports are usually close, but they can miss dormers, low-slope sections or overhangs hidden by trees. A field measurement settles disagreements.
Why are bundles rounded up?
Shingles come in bundles, typically three per square, so you can’t buy a fraction.
Does this work for slate?
The squares math is the same, but slate is priced very differently. Use a slate contractor’s per-square price.