Roofing Square Calculator — Convert Sq Ft to Squares

What Is a Roofing Square?

A "square" is roofing shorthand for 100 square feet of roof surface. It's the unit manufacturers price by, contractors bid by, and suppliers order by. A 25-square roof means 2,500 square feet of actual roof surface area (not footprint — surface).

Getting the number right means starting with the roof footprint (length × width from above), multiplying by the pitch multiplier to get true roof surface, dividing by 100 to get squares, then padding for waste.

Waste Factor: Why It Matters

You will not use every square inch of every bundle. Cuts around vents, ridges, valleys, hip caps, starter courses, and the ones the apprentice tears while unwrapping — all of it eats into your yield. Standard ballpark:

• 10%: simple gable roof, no valleys, straightforward layout.
• 12–13%: typical residential with a couple of hips or valleys.
• 15%+: complex hip roof, lots of valleys, dormers, cut-ups.

Bundles Per Square

Most 3-tab and architectural asphalt shingles are packaged 3 bundles per square. Heavier premium/designer shingles are often 4 or 5 bundles per square. This calculator assumes standard 3-bundle packaging, so verify against the specific SKU you're ordering before you cut a PO.