Roofers measure in squares: 100 sq ft of roof surface. A sloped roof has more surface than the flat footprint under it, so pitch matters.
Roofing calculator
Measure the footprint (or enter the roof area), add the overhang and pitch.
Enter your numbers to see the result.
From footprint to roof area
Roof surface = plan area x pitch factor. The pitch factor is √(1 + (rise/12)²): 1.054 for a 4/12 roof, 1.118 for 6/12 and 1.202 for 8/12.
Example: a 40 x 30 ft house with 12 in overhangs is 42 x 32 = 1,344 sq ft in plan. At 6/12 that is 1,503 sq ft of roof, 15 squares. With 10% for waste, about 50 bundles.
Bundles per square
Most asphalt shingles, both 3-tab and architectural, pack 3 bundles per square, as printed on GAF’s Timberline wrappers. A few heavier styles pack 4, so check the wrapper.
Waste
Simple gable roofs need less extra than roofs with hips, valleys and dormers, where every cut wastes shingle. Starter strip and ridge cap are often separate products.
Sources
Sources last checked 1 November 2026.
Frequently asked questions
How many bundles of shingles are in a square?
Most asphalt shingles take 3 bundles to cover a square (100 sq ft). Check the wrapper.
How do I find my roof pitch?
Measure how many inches the roof rises over 12 in of level run, or use the roof pitch calculator.
How many squares is a 2,000 sq ft house?
It depends on the footprint, overhang and pitch, not the living area. Measure the footprint and use the calculator.