How the roof area calculator works
Why pitch multiplies area
A sloped plane covers more surface than its shadow: the hypotenuse of the pitch triangle. At 6/12 (6" rise per 12" run) the factor is √(1+0.5²) ≈ 1.118; at 12/12 it is 1.414. Footprint × factor = one roof plane's area; a simple gable has two planes that together cover the footprint twice — the arithmetic the calculator assembles.
The square: roofing's native unit
A "square" is 100 sq ft of roof — the unit every quote, bundle count, and material order uses. Three bundles of standard asphalt shingles cover one square. The footprint-to-squares conversion (with pitch and complexity) is the first number in every roofing conversation, and knowing it independently makes quotes legible.
Complexity is the honest add-on
Valleys, hips, dormers, and intersecting ridges add cutting, waste, and time: simple gables run ~0.95× the plane math, hips +10%, dormered roofs +25%. Complexity also drives labor cost per square — a 25-square simple gable and a 25-square dormered roof are different projects wearing the same number.