How it works
- Area to order = roof area × (1 + waste)
- Squares = area to order ÷ 100
- Bundles = squares × bundles per square, rounded up
- Underlayment rolls = area to order ÷ roll coverage, rounded up
- Nails = squares × 80 shingles × nails per shingle
Example: a 1,500 square foot roof with 10 percent waste is 1,650 square feet, or 16.5 squares. At 3 bundles per square that is 49.5, so you order 50 bundles. Underlayment is 1,650 ÷ 400 = 4.1, so 5 rolls of #15 felt. Nails are 16.5 × 320 = 5,280.
Bundles and squares
A roofing square is 100 square feet. Most three-tab and architectural shingles are packed 3 bundles to a square, so one bundle covers about 33 square feet. Heavier premium shingles can take 4 or 5 bundles per square. The number is printed on the wrapper.
How much waste to add
Ten percent is a common allowance for a simple gable roof. Use about 15 percent for a roof with hips and valleys, and more for a roof with many dormers or angles. Starter strips along the eaves also come out of this allowance if you cut them from full shingles.
Underlayment, nails and ridge cap
A roll of #15 felt covers about 400 square feet and a roll of #30 felt covers about 200. Synthetic rolls are often 1,000 square feet. Standard nailing is 4 nails per shingle, which works out to about 320 nails per square. High wind areas call for 6 nails per shingle, about 480 per square. Ridge cap coverage varies by product, commonly 20 to 33 linear feet per bundle, so check the wrapper and change the number above.
Common questions
How many bundles of shingles are in a square?
Usually 3. Some heavier architectural and designer shingles take 4 or 5 bundles per square. The wrapper tells you.
How many bundles of shingles do I need for a 1,500 square foot roof?
About 50 bundles, using 3 bundles per square and 10 percent waste. Without any waste it would be 45.
How many square feet does one bundle of shingles cover?
About 33 square feet when there are 3 bundles to a square.
How many roofing nails do I need per square?
About 320 with standard nailing of 4 nails per shingle, or about 480 with 6 nails per shingle in high wind areas.
Is roof area the same as my house square footage?
No. The roof is larger because it slopes and overhangs the walls. Use the house size option above, or the roof area calculator, to convert.