Free tool
Shingle Calculator
Know your roof area? Enter it with your waste allowance and the bundles per square on your shingle wrapper to get how many bundles of shingles to buy.
How we calculate it
- Pitch multiplier = √(1 + (rise ÷ 12)²)
- Roof area = footprint length × width × pitch multiplier (or the area you enter)
- Squares = roof area ÷ 100, then × (1 + waste %)
- Bundles = squares with waste × the bundles per square on your wrapper, rounded up
The footprint method assumes one pitch over the whole roof. Ridge caps, starter strips, underlayment, flashing and tear-off are not included. This is an estimate, not a quote.
For roofers
How to use this tool
- Measure the roofEnter the footprint with overhangs and the pitch, or the roof area if you know it.
- Set the wasteChoose a waste allowance for cuts and the roof's shape.
- Enter your shinglesType the bundles per square from your shingle wrapper to get the bundle count.
Frequently asked questions
How many squares is 1,800 square feet of roof?
A square is 100 square feet, so 1,800 square feet of roof surface is 18 squares. With a 10% waste allowance that becomes 19.8 squares. To turn squares into bundles, multiply by the bundles per square printed on your shingle wrapper and round up to a whole bundle.
How many bundles of shingles are in a square?
It varies by product, so this calculator does not assume a number. Your shingle wrapper or the manufacturer's spec sheet says how many bundles make a square, or how many square feet one bundle covers. If it gives square feet per bundle, divide 100 by that number and enter the result.
What is a roofing square?
A square is 100 square feet of roof surface. A roof with 2,000 square feet of surface is 20 squares. Shingles, underlayment and labor are often priced per square, so the calculator shows your roof in squares before and after the waste allowance you choose, ready to compare with a supplier's price.
Is this a roofing quote?
No. It is a material estimate from the size and pitch you enter. Valleys, dormers, ridge caps, starter strips, flashing and tear-off are not included, and waste depends on the roof's shape. A roofer who measures the roof in person can give you an exact quantity and a price.