Roofing Square

A roofing square equals 100 square feet of roof surface. The whole industry — manufacturers, suppliers, and contractors — uses this unit because it makes ordering simpler and the math more intuitive. A 2,000 sq ft roof is 20 squares. A 3,500 sq ft roof is 35 squares. Most architectural shingles come 3 bundles per square, meaning 3 bundles cover 100 sq ft. Premium designer shingles can be 4–5 bundles per square. Always check the bundle's coverage rate (printed on the wrapper) when ordering. When measuring for shingles, calculate your sloped roof area (footprint × pitch multiplier), add 10–18% for waste depending on roof complexity, then divide by 100 to get squares. Round up — partial bundles aren't a thing. Underlayment also ships per square. Synthetic underlayment rolls typically cover 10 squares (1,000 sq ft) per roll. Felt paper rolls cover about 4 squares (400 sq ft). For estimating: most roofers think in dollars per square (e.g. "$450/square installed"). This is just a per-sqft rate × 100 — useful shorthand that makes back-of-napkin math fast on a sales call.