Roof Shingle Quantity Calculator
Understanding Your Roof Shingle Needs
Estimating the correct number of shingles for your roof is crucial for any roofing project. Over-ordering leads to unnecessary costs and waste, while under-ordering can cause delays and additional shipping fees. Our Roof Shingle Quantity Calculator helps you get a precise estimate based on your roof's dimensions and pitch.
How to Measure Your Roof
For a simple gable roof, measure the total length of the roof (eave to eave) and the total width (rake to rake). If your roof has multiple sections or complex shapes, you'll need to break it down into simpler rectangles or squares, calculate each section individually, and then sum them up. Always measure carefully and consider adding a small buffer for errors.
What is Roof Pitch?
Roof pitch describes the steepness of your roof. It's typically expressed as a ratio, such as "6/12" or "8/12". The first number (the "rise") indicates how many inches the roof rises vertically for every 12 inches it extends horizontally (the "run"). A higher rise means a steeper roof. Steeper roofs have a larger surface area than their flat footprint, requiring more materials. Our calculator uses the 'rise' component of your pitch (e.g., enter '6' for a 6/12 pitch) to accurately adjust the surface area.
Shingle Coverage per Bundle
Shingles are typically sold in "bundles." The coverage area of a single bundle can vary depending on the type of shingle (e.g., 3-tab, architectural, designer) and the manufacturer. A common coverage for 3-tab shingles is around 33.3 square feet per bundle, while architectural shingles might cover slightly less, like 32.3 square feet. Always check the manufacturer's specifications for the specific shingles you plan to use.
The Importance of a Waste Factor
Even with perfect measurements, some material will be wasted due to cuts, trimming around vents or chimneys, and potential errors. This is why a "waste factor" is essential. For simple gable roofs, a 10% waste factor is often sufficient. For more complex roofs with multiple valleys, hips, or dormers, you might need to increase this to 15% or even 20% to ensure you have enough material.
Example Calculation
Let's say you have a roof section that is 40 feet long and 25 feet wide, with a 6/12 pitch. You're using shingles that cover 33.3 sq ft per bundle, and you want to include a 10% waste factor.
- Footprint Area: 40 ft * 25 ft = 1000 sq ft
- Pitch Adjustment: For a 6/12 pitch, the actual surface area is about 1.118 times the footprint.
- Actual Roof Area: 1000 sq ft * 1.118 = 1118 sq ft
- Total Squares: 1118 sq ft / 100 sq ft/square = 11.18 squares
- Bundles (before waste): 1118 sq ft / 33.3 sq ft/bundle = 33.57 bundles
- Bundles (with 10% waste): 33.57 * 1.10 = 36.93 bundles
- Rounded Up: You would need to purchase 37 bundles of shingles.
Use our calculator above to quickly determine your specific shingle requirements!