Construction
Square Feet to Roofing Squares Calculator
A roofing square is 100 square feet. Enter your roof's footprint, pitch, and a waste allowance to convert to roofing squares and the number of shingle bundles to order.
Quick answer: One roofing square equals 100 square feet, so divide your total roof area by 100 to get squares. A 1,800 sq ft roof is 18 squares before pitch and waste; most shingles come 3 bundles to a square.
How it works
1. Start with footprint area
Measure the flat ground area your roof covers in square feet (length times width of each roof section). This is the footprint, not the sloped surface.
2. Adjust for pitch
A sloped roof has more surface than its footprint. Multiply by the NRCA pitch factor — about 1.05 for a 4:12 roof, up to 1.41 for a 12:12 — to get true sloped area.
3. Divide by 100 and add waste
Divide the sloped area (plus 10–15% waste) by 100 to get roofing squares. Multiply squares by 3 for the number of standard shingle bundles to order.
Frequently asked questions
How many square feet are in a roofing square?
A roofing square is exactly 100 square feet of roof surface. It's the standard unit roofers use to price and order materials, so a 2,000 sq ft roof is 20 squares.
How many bundles of shingles are in a square?
Most architectural and 3-tab shingles come three bundles to a square (100 sq ft). Heavier or designer shingles can run four or five bundles per square — check the wrapper.
Does roof pitch change the number of squares?
Yes. A steeper roof has more surface area than its flat footprint, so the same footprint needs more squares. This calculator applies the standard NRCA pitch multiplier.