Turn a building footprint and roof pitch into a full shingle order: sloped roof area, squares, bundles with waste, underlayment rolls, ridge cap for the ridge and hips, starter strip and drip edge for the eaves and rakes, and pounds of roofing nails. Coverage figures follow common manufacturer specs — 3 bundles per square, 25 ft per ridge-cap bundle, 120 ft per starter bundle — and every one is editable.
Not sure of the slope? Measure it first with the roof pitch calculator. Once the roof is sorted, the gutter size calculator sizes the gutters and downspouts for the same roof area, and the percentage calculator helps compare supplier quotes.
Frequently asked questions
How many bundles of shingles do I need?
Find the sloped roof area, divide by 100 to get squares, add waste, and multiply by the bundles per square — 3 for standard 3-tab and most architectural shingles, since each bundle covers about 33.3 sq ft. A 40 × 30 ft house with a 6:12 roof has 1,342 sq ft of roof, or 13.4 squares; with 10% waste that is 14.8 squares, or 45 bundles. Some heavy designer shingles are 4 or 5 bundles per square, so check the wrapper and change the setting if yours differ.
How does roof pitch change the amount of shingles?
A pitched roof has more surface than the footprint it covers. The multiplier is the square root of 1 plus (rise ÷ 12) squared: 1.054 for 4:12, 1.118 for 6:12, 1.202 for 8:12, and 1.414 for 12:12. Multiply the plan area (the roof seen from above, overhangs included) by that factor to get the real area you shingle. If you don't know your pitch, measure the rise over a 12 in level held against the roof or rafter, or use the roof pitch calculator.
How much waste should I add for roofing?
About 10% is typical for a simple gable roof with long, straight courses. Hip roofs, valleys, and dormers need more cutting, so 15% is the common allowance; very cut-up roofs can reach 20%. The calculator switches the default when you pick gable or hip, but you can type any figure. Waste covers cuts at rakes and hips, starter courses on some installs, and a few damaged shingles. Leftover full bundles are usually returnable, so rounding up costs little. Running short mid-job risks a color mismatch between production lots.
How many rolls of underlayment and how many nails?
Synthetic underlayment typically comes in rolls covering about 10 squares (1,000 sq ft). Traditional #15 felt covers about 4 squares per roll and #30 felt about 2 squares, after overlaps. On slopes from 2:12 up to 4:12 the IRC (R905.1.1) requires two layers under shingles, and the calculator doubles the roll count for you in that range. For nails, most manufacturers require 4 nails per shingle, about 320 per square, and 6 nails in high-wind zones, about 480. At roughly 150 1-1/4 in roofing nails per pound, that is around 2 lb per square. Your shingle wrapper lists the required nail count for the warranty — it wins over any rule of thumb.
What does this calculator not include?
It counts shingles, underlayment, ridge cap, starter strip, drip edge, and nails. It does not count ice-and-water shield (usually required along eaves in cold climates and in valleys), valley metal, step and chimney flashing, pipe boots, ridge vents, or replacement decking. The ridge and edge lengths it computes assume a simple rectangular gable or hip roof; for L-shaped or complex roofs, measure each plane or type the real ridge, hip, eave, and rake lengths into the override fields. Ask your supplier for the full accessory list.