Shingle Calculator
Calculate exactly how many bundles of asphalt shingles you need for a roof. Accounts for pitch, waste factor, and roof complexity.
Floor plan area, not the slanted roof surface.
Rise over run. Standard residential is 4:12 to 9:12.
Affects waste factor: gable 10%, hip 15%, complex 20%.
Override if you have specific waste estimates for this job.
Materials needed
Based on 3 bundles per square
- Roof squares
- 22.36squares
- With waste
- 24.6squares
- Pitch multiplier
- 1.118
- Waste factor applied
- 10%
Add ridge cap shingles separately (typically 1 bundle per 35 linear ft of ridge).
Add starter strip and underlayment to your order.
Always verify measurements on-site before ordering.
How this calculator works
The roofing shingle calculator determines exactly how many bundles of asphalt shingles your roof needs based on three factors: the building footprint, the roof pitch, and the roof complexity.
Step 1: Building footprint
Start with the footprint — the floor plan area of the home, not the actual slanted roof surface. A 40 × 50 foot home has a 2,000 sq ft footprint regardless of roof pitch.
Step 2: Pitch multiplier
Steeper roofs have more surface area than their footprint suggests. The calculator uses the Pythagorean theorem to convert pitch into a multiplier. A 6:12 pitch gives a 1.118 multiplier, meaning that same 2,000 sq ft footprint actually has 2,236 sq ft of roof surface.
Step 3: Waste factor
Every roof needs extra shingles for cuts, starters, and mistakes. Simple gable roofs run 10% waste; hip roofs need 15%; complex roofs with valleys, dormers, and multiple planes often need 20% or more.
Step 4: Bundle conversion
Standard architectural shingles come 3 bundles per square (100 sq ft). The calculator rounds up to whole bundles because partial bundles aren't sold. Premium and designer shingles may run 4 or 5 bundles per square — verify with your supplier.
Frequently asked questions
- How many bundles of shingles do I need per square?
- Most architectural and 3-tab asphalt shingles come 3 bundles per square (100 sq ft of roof coverage). Some premium and designer shingles run 4 or 5 bundles per square — always check your specific product.
- What waste factor should I use?
- Industry standards: 10% for simple gable roofs, 15% for hip roofs (more cuts), and 20% for complex roofs with multiple valleys, dormers, or cut-ups. Add 5% more if the roofers are inexperienced or the shingles are large-format.
- Does this include ridge cap shingles?
- No — ridge cap shingles are ordered separately. Plan on roughly 1 bundle of hip and ridge cap per 35 linear feet of ridge and hip line.
- How does roof pitch affect shingle quantity?
- Pitch determines how much more surface area the roof has compared to the building footprint. A 6:12 pitch roof has about 12% more surface area than the footprint; a 12:12 roof has about 41% more. The calculator applies this multiplier automatically.
- Should I use this calculator for insurance estimates or bids?
- This calculator gives a solid initial estimate, but always verify with on-site measurements before submitting a formal bid or insurance estimate. Eave-to-ridge measurements, dormer counts, and valley footage need direct measurement.