Estimate roofing squares, shingle bundles, and material cost in seconds. Enter your roof footprint and pitch, we handle the math.
Estimates for planning only. Always confirm measurements and order a little extra for waste and cuts.
Roofers and suppliers measure roofs in squares, where one square equals 100 square feet of roof surface. This calculator turns your roof's footprint and pitch into the squares and shingle bundles you'll need, so you can sanity-check a quote or plan a DIY job.
The math is straightforward once you have two numbers: your roof's footprint (the ground area it covers) and its pitch (how steep it is). A steeper roof has more surface area than its footprint, so we multiply by a pitch factor:
Roof area = footprint × pitch factor × (1 + waste %)Squares = roof area ÷ 100 · Bundles = squares × 3
Pitch is written as rise-over-run (inches of rise per 12 inches of run). The steeper the pitch, the larger the multiplier:
If you're not sure of your pitch, a 6/12 is the most common residential slope and a safe default for a rough estimate.
Three inputs drive everything: the footprint you type, the pitch you select, and the waste percentage, which starts at 10. The tool multiplies footprint by the pitch factor for that slope, adds the waste percentage on top, divides by 100 to get roofing squares, then multiplies squares by three for bundles and rounds bundles up, because you buy full bundles. The pitch factors are plain geometry, the slope length per unit of horizontal run, so a 6/12 roof covers about 1.118 times its footprint and a 12/12 about 1.414. Fill in a price per square and it multiplies that by your squares. That price is yours, not ours. The tool carries no price list, and the cost line is materials only.
It does not measure your roof. Footprint is whatever you type, and the common mistake is typing the heated floor area of the house, which leaves out every overhang. It also has no idea how cut up the roof is. Hips, valleys, dormers, chimneys and skylights all create offcuts, and the flat waste percentage is the only place that gets accounted for, so raise it toward 15 on a complicated roof.
Two more limits worth saying plainly. The bundle count assumes three bundles to a square, which holds for standard three-tab and architectural shingles but not for designer lines that run four or five, so read the wrapper before you order. And this sizes field shingles only: ridge cap, starter strip, underlayment, ice-and-water shield, drip edge, vents and nails are not in the count, and neither is labor, tear-off, disposal, decking repair or the permit. It is a takeoff for one material, not a bid. For pricing a whole job, or for building the paperwork that goes around it, start from the full list of free tools.
The ground area the roof covers, overhangs included, not the heated square footage of the house. Eaves and rakes are real roof surface that needs shingles. If all you have is the floor area, expect the result to come in low, and measure the actual roof outline before you place an order.
They are geometry, not an opinion. Pitch is rise over run in inches, and the multiplier is the length of the sloped surface per unit of flat run, so a 4/12 works out to about 1.054 and a 12/12 to 1.414. If you do not know your pitch, 6/12 is the most common residential slope and a reasonable default for a rough number.