How to Calculate Roof Shingles
Roofing materials are sold in "Squares." One Square equals 100 square feet of roof area. Because roofs are sloped, the actual surface area is larger than the flat footprint of your house. Our calculator applies a pitch multiplier to your footprint to find the true surface area.
Hip Roofs vs. Gable Roofs
A common mistake is multiplying the area by the number of planes. A hip roof (4 planes) doesn't have 4 times the area of a shed roof; it just has more complex angles. Our calculator correctly adds a 5% waste buffer for the diagonal cuts required on hip roofs, rather than inflating the total square footage.
Pitch in Degrees, Rise & Run
Roof pitch is usually written as a fraction like "6/12" (6 inches of rise per 12 inches of run), but it can also be expressed in degrees. A 6/12 pitch is about 26.6°, and a 4/12 pitch is about 18.4°. If you need to convert between rise/run, degrees, and percentage slope — or you're working on something other than a roof, like a ramp or drainage line — use our dedicated Slope & Pitch Calculator.
Need to know how long to cut your actual rafters, not just the shingle area? Use our Roof Rafter Length Calculator to get the exact board length from your run, pitch, and overhang.
Frequently Asked Questions
How many bundles of shingles in a square?
There are exactly 3 standard bundles of architectural shingles in 1 Square (100 sq ft).
What is the pitch multiplier for an 8/12 roof?
An 8/12 roof has a pitch multiplier of approximately 1.15. This means the actual roof surface is 15% larger than the flat footprint of the house.
What is a 6/12 roof pitch in degrees?
A 6/12 pitch is approximately 26.6 degrees. Use our Slope & Pitch Calculator to convert any rise/run combination into degrees or percentage slope.
How many roof vents does my attic need?
Use our Roof Vent Sizing Calculator for the exact intake and exhaust net free area required under IRC R806, based on your attic size and roof pitch.