How this calculation works
- Net area comes from footprint × pitch factor, or from a number you already measured.
- Waste multiplies net area. Field shingles = that area. Squares = area / 100. Bundles = squares × bundles per square, rounded up.
- Starter and ridge use linear coverage printed on those products, not the field-shingle square count.
squares = area × (1+waste%) / 100; bundles = ceil(squares × bundlesPerSquare); starter = ceil(eaves / coverage); ridge = ceil(ridge / coverage)
What to do next
- Match bundles-per-square and ridge coverage to the exact product on the pallet tag.
- Order extra from the same lot; dye lots do not always match next season.
- Ice-and-water shield and underlayment are sold by the roll and are not included here.
FAQ
- Why round bundles up?
- You cannot buy 0.4 of a bundle from most yards, and running short on a roof is worse than a leftover bundle from the same lot.
- Can I use leftover 3-tab as ridge?
- Some crews cut 3-tab for cap on a matching 3-tab roof. Laminate roofs usually want a matching hip-and-ridge product. Follow the manufacturer if you care about the warranty.
Sources
- US asphalt shingles are commonly packaged 3 bundles per square (100 sq ft); verify the wrapper
- Starter and ridge coverage vary by product; defaults are typical planning lengths, not a specific SKU
Cost defaults are typical US planning bands, last reviewed 2026-08-25. Edit the price fields on this page rather than treating them as a local market index.