40×30 roof, 6/12 pitch, 10% waste
- Area ≈ 1,488 sq ft
- Squares ≈ 16.4
- Bundles ≈ 49
construction calculator
Roofing Shingles Calculator
Estimate roofing squares and bundles needed for asphalt shingles, factoring in pitch and waste.
Results
- Roof squares
- 14.78
- Shingle bundles
- 44.35
How to use this calculator
- Enter roof length and width in feet.
- Enter pitch multiplier and waste percentage.
- We calculate roof area, squares, and bundles (3 bundles per square).
Inputs explained
- Roof length/width
- Plan view dimensions of the roof section in feet.
- Pitch multiplier
- Factor for roof slope (e.g., 1.12 for 4/12, 1.24 for 6/12).
- Waste %
- Extra for cuts, hips/valleys, and starter/ridge pieces.
How it works
Roof area = length × width × pitch factor. One square = 100 sq ft. Waste increases squares by the given percentage.
Bundles = squares × 3 (typical for asphalt shingles).
Formula
Area = L × W × pitch factor\nSquares = (Area ÷ 100) × (1 + waste%)
When to use it
- Estimating shingles for asphalt roof replacements.
- Comparing waste assumptions for complex roofs.
- Budgeting bundles before ordering or requesting quotes.
Tips & cautions
- Use higher waste for cut-up roofs, many valleys, or heavy starter/ridge requirements.
- Pitch multipliers vary by slope—double-check your roof pitch to pick the right factor.
- Round up bundles; extras cover repairs and color matching later.
- Assumes rectangular footprint; complex roofs may need per-plane calculations.
- Uses 3 bundles per square; check manufacturer if bundle coverage differs.
- Does not include underlayment, ice/water shield, or accessories.
Worked examples
Steeper 8/12 pitch, 15% waste
- Pitch factor ≈ 1.32
- Squares increase accordingly.
Deep dive
This roofing shingles calculator converts roof dimensions, pitch factor, and waste into squares and bundle counts. Enter length, width, pitch multiplier, and waste to size asphalt shingle orders.
Use higher waste for complex roofs and remember bundles per square can vary—verify with your shingle manufacturer.
FAQs
- Does this include ridge cap or starter strips?
- Add 1–2 extra bundles for ridge/hip coverage depending on roof layout.
- What about multi-plane roofs?
- Break the roof into rectangles, run this calculator per section, then sum the results.
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Verify dimensions and pitch on site. Structural loads and installation best practices remain your responsibility.