Squares method
One roofing square = 100 sq ft of roof surface. Roof area ≈ plan area × pitch factor. Squares = roof area ÷ 100. Add 10–15% waste for starter, hips, valleys, and ridge. Most asphalt bundles cover about ⅓ square (3 bundles per square)—read the wrapper for exact coverage.
Worked example
Plan 40 × 25 ft at 6/12: factor √(1+0.25)=1.118. Roof area ≈ 1,118 sq ft ≈ 11.18 squares. With 10% waste → 12.3 squares ≈ 37 bundles at 3 per square.
Limits of a rectangle model
Complex roofs need plane-by-plane takeoff. Use this estimator for simple gables and quick budgets, then verify with a roofer’s measurements. Find pitch first with the roof pitch calculator.
Common mistakes
- Ignoring starter strip and ridge cap bundles.
- Assuming every bundle is exactly 1/3 square.
- Skipping underlayment and ice-barrier quantities in cold climates.
| Item | Typical value |
|---|---|
| 1 square | 100 sq ft of roof surface |
| Bundles per square | ~3 (asphalt) |
| Waste — simple gable | ~10% |
| Waste — hip / complex | ~15% |
Assumptions and limits
The roofing shingles calculator results are planning estimates for rectangular or cylindrical shapes with uniform depth. Real sites have slopes, voids, and product variation. Always confirm coverage with the manufacturer label and local building practices before you buy large quantities.
Unit toggles switch input labels between US imperial and metric. Shareable URLs store your inputs in the query string for convenience, while the canonical tag stays on the clean page URL so search engines do not index every parameter combination.
Shopping checklist
- Write down the calculator outputs (volume, bags, or piece counts) and round up for waste.
- Call your supplier for density, dye lot, or delivery minimums when ordering bulk material.
- Check access for trucks, wheelbarrows, and staging space before delivery day.
- Photograph existing conditions so you can revisit dimensions if a helper measures differently.
Separate ridge, hip, and starter products from field bundles when you place the order so waste factors stay clear.
FAQ
How many bundles in a square?
Typically three bundles per square for many asphalt products, but always read the bundle label—coverage varies.
Related guides
Sources
- GAF – Manufacturer coverage practice (example) Used for: Bundles-per-square industry practice; always read the bundle label. Checked .
Estimates only—confirm bag yields on the product label and check local building codes before you pour or order. Not affiliated with QUIKRETE, Sakrete, Sonoco, or any manufacturer named in the sources. Found an error? Tell me.
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