Roof Shingle & Material Takeoff
Plan area and pitch to real roof area, then squares, bundles, underlayment, starter, ridge cap, drip edge, nails, and the 2026 material cost.
Roof area is bigger than floor area: a 6:12 pitch multiplies the plan by 1.118, a 12:12 by 1.414. Shingles, underlayment, and starter all scale with the roof, not the house.
How the math works
- Pitch multiplier: roof area = plan area × √(144 + pitch²) ÷ 12. 4:12 = 1.082, 6:12 = 1.118, 8:12 = 1.202, 12:12 = 1.414. That is why a 1,000 sq ft footprint carries 1,118 sq ft of roof at 6:12.
- Squares and bundles: 1 square = 100 sq ft of roof; asphalt bundles cover 33⅓ sq ft, so 3 bundles per square. Hips and valleys run 10 to 20% waste, plain eaves 5%.
- Underlayment: one 100 sq ft roll per square (synthetic), starter roll at the eaves = eave footage ÷ 33 ft. In ice-dam climates, 3 ft of self-adhering shield along the eave is code in many jurisdictions.
- Ridge: ridge cap ships in 10½ ft bundles, one per 10 ft of ridge; ridge vent is 1:1 with the ridge length and gives about 50 CFM per foot, which is what a 6:12 roof needs to meet the 1:150 net-vent rule.
- Drip edge & nails: drip edge runs at eaves and rakes (10 ft lengths); 4d 6d roofing nails at about one 5 lb box per 2 squares.
How many squares of shingles for a 2,000 sq ft house?
Roof squares are not floor sq ft: a 1,000 sq ft footprint at 6:12 is 1,118 sq ft of roof, so about 12 squares with waste, which is 36 bundles.
How many bundles per square of roof?
Three bundles per square (100 sq ft) for standard asphalt, 3-tab or architectural. Order 10% more on a roof with hips and valleys and you will not run short on the last square.
Do I need starter shingles and drip edge?
Yes: starter at the eaves gives the seal and the 4 in headlap strip, and drip edge (code since the 2011 IRC) sheds water into the gutter instead of into the fascia.