Formula
The page rounds up to a whole bundle:
bundles = ceil(squares × bundles per square)
Three-tab shingles are counted as 3 bundles per square. Architectural shingles are counted as 4. The roofing page is the one that converts area into squares.
Assumptions
- A square is 100 square feet and already includes any waste you want.
- The bundle count matches the style you select.
- A partial bundle is bought whole.
Worked example
Eighteen squares of 3-tab shingles need 54 bundles.
Input definitions
- Bundle
- The package the shingles are sold in. Several bundles make one square.
- Square
- 100 square feet of roof.
Limitations
Ridge, starter, and hip pieces are often a different product. Read the coverage on the wrapper before ordering.
Questions
Why would a square be 4 bundles?
Many architectural shingles are packaged that way. Three-tab shingles are commonly 3 bundles per square.
Where do I get the square count?
Divide the sloped area by 100 on the roofing page, after waste.