Roofing Calculator: Squares and Bundles by Pitch
Enter the building footprint, overhang and pitch to estimate roof area, roofing squares and shingle bundles. The calculator multiplies plan area by the pitch factor, divides by 100 to get squares, then adds waste: about 10 percent for gable roofs and 15 percent or more for hip roofs.
Order: 26.4 squares · 80 bundles
Roof surface 2,357 ft² (23.6 net squares) · pitch factor 1.118
Pitch factor table
| Pitch | Pitch factor | Roof area per 1,000 ft² of plan |
|---|---|---|
| 3/12 | 1.031 | 1,031 ft² |
| 4/12 | 1.054 | 1,054 ft² |
| 5/12 | 1.083 | 1,083 ft² |
| 6/12 | 1.118 | 1,118 ft² |
| 7/12 | 1.158 | 1,158 ft² |
| 8/12 | 1.202 | 1,202 ft² |
| 9/12 | 1.250 | 1,250 ft² |
| 10/12 | 1.302 | 1,302 ft² |
| 12/12 | 1.414 | 1,414 ft² |
Kansas roofing notes
- Many Kansas homeowners choose impact-resistant shingles rated UL 2218 Class 4 because of hail exposure, and some insurers offer premium credits for them. Confirm pricing and availability with your supplier.
- Roofing contractors working in Kansas must register with the Kansas Attorney General under the Kansas Roofing Registration Act.
- Read the full Kansas hail and roofing estimating guide or order a roofing takeoff.
Frequently asked questions
How many square feet are in a roofing square?
One roofing square covers 100 square feet of roof surface. Most architectural shingles are packaged three bundles per square, but always check the manufacturer's coverage.
How do I account for roof pitch?
Multiply the plan area by the pitch factor, which is the square root of 1 plus (rise ÷ 12) squared. A 6/12 roof has a factor of about 1.118, so 2,000 square feet of plan area becomes about 2,236 square feet of roof surface.
How much waste should I add for shingles?
About 10 percent for a simple gable roof and 15 percent or more for hip roofs, valleys, dormers and cut-up roofs. Starter, ridge cap and underlayment are separate line items.
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