The Primary Defense System
Asphalt shingles are the most common roofing material in North America. They are cost-effective, easy to install, highly fire-resistant, and can last anywhere from 20 to 50 years depending on the architectural grade.
When a massive pallet of shingles is dropped in your driveway by a crane, the shear volume can seem overwhelming. However, understanding how shingles are packaged and sold is the key to accurately pricing out a new roof.
If you underestimate your required shingles, the roofing crew will have to stop working and leave your roof exposed to the weather while you order more. If you overestimate, you will be stuck paying massive restocking fees to return heavy bundles to the supply yard.
Bundles and Squares
In the roofing industry, nobody talks in terms of "square feet." They talk in terms of "Squares."
- One Roofing Square = Exactly 100 square feet of roof surface area.
Because a "Square" of shingles weighs roughly 240 pounds, it is far too heavy for a human to carry up a ladder. Therefore, manufacturers break one Square down into smaller, manageable packages called Bundles.
- For standard 3-tab shingles, it takes exactly 3 Bundles to make 1 Square.
- For heavier, thicker Architectural shingles, it may take 4 Bundles to make 1 Square (depending on the brand).
(Our calculator assumes the universal industry standard of 3 bundles per square).
How to Calculate Shingle Bundles
To calculate how many bundles of shingles you need, you must know the exact surface area of your roof, convert that into Squares, and then multiply by bundles.
(Note: If you do not know the actual sloped surface area of your roof, please use our Roof Area Estimator first. You cannot use the flat footprint of your house!)
The Formula
- Determine the true sloped surface area of your roof in square feet.
- Divide the total surface area by 100 to find the total number of Squares.
- Multiply the number of Squares by 3 to find the number of Bundles.
- Add a 10% to 15% Waste Factor (to account for cutting shingles in valleys and edges).
- Round up to the nearest whole bundle.
Total Bundles = Roundup(((Surface Area ÷ 100) × 3) × 1.15)
Example Calculation
You have determined that your sloped roof surface area is exactly 2,250 square feet. You are installing standard asphalt shingles.
- Convert to Squares:
2,250 ÷ 100 = 22.5 Squares - Convert to Bundles:
22.5 × 3 = 67.5 Bundles - Add 15% Waste for a complex roof:
67.5 × 1.15 = 77.62 Bundles - Round up: 78 Bundles.
You should order 78 bundles of shingles.
Don't Forget Starter Shingles and Caps
A common amateur mistake is buying regular shingles and trying to use them for everything.
You must also order specialized Starter Shingles (which have a unique adhesive strip to lock down the very first row against high winds) and Ridge Cap Shingles (which are pre-bent to cover the peak of the roof). Regular shingles will crack if you try to bend them over the ridge in cold weather.