Roofing Calculator
Calculate bundles, squares, weight, and installed cost for any roof size and pitch. Covers architectural shingles, metal, wood shakes, slate, tile, and flat roofing. Step-by-step slope factor derivation and waste factor guidance.
Roof dimensions
Material & waste
| Footprint area | 1,500 sq ft |
| Actual roof area | 1,677 sq ft |
| With waste (10%) | 1,845 sq ft |
| Roofing squares | 18.4 |
| Main bundles | 56 |
| Starter bundles | 1 |
| Ridge cap bundles | 1 |
| Total bundles | 58 |
| Total weight | 5,903 lbs (2.68 t) |
| Eave linear ft (est.) | 77 lf |
Page types — explore all 5 axes
How to calculate roofing bundles
Start with your floor-plan footprint (the area measured at ground level). Multiply by the slope factor — √(rise² + 12²) ÷ 12 — to get actual roof area. Add a waste allowance (10% for simple gable, up to 25% for cut-up roofs), divide by the square footage per bundle for your chosen material, and round up. Most architectural shingles cover ~33 sq ft per bundle, so a 1,500 sq ft footprint with 6/12 pitch and 10% waste needs roughly 51 bundles of field material plus starter and ridge cap.
What is a roofing square?
A roofing square equals 100 square feet of actual roof surface area (after applying the slope factor). Contractors price labor and materials per square. A typical 1,500 sq ft ranch home with a 6/12 pitch has about 17 roofing squares before waste.
Frequently asked questions
How many bundles of shingles do I need for 1,500 sq ft?▾
For a 1,500 sq ft footprint with a 6/12 pitch and simple gable waste (10%), you need approximately 48 field bundles of architectural shingles. Add 2 starter bundles and 1 ridge cap bundle for a total of ~51 bundles.
What pitch factor should I use?▾
The slope factor is √(rise² + 144) ÷ 12. For the most common 6/12 pitch it is 1.1180, meaning your actual roof area is 11.8% larger than your floor plan. The calculator above applies this automatically.
How much does a new roof cost?▾
Based on RSMeans 2024 data, architectural asphalt shingles run $350–$600 installed per square (100 sq ft). A 1,500 sq ft home with 17 squares costs roughly $6,000–$10,000 installed. Metal roofing runs $700–$1,400 per square; slate and tile $1,200–$2,500+.
What is the waste factor for a hip roof?▾
Hip roofs use 15% waste allowance vs 10% for simple gable, because hip ends require diagonal cuts that produce more off-cut waste. Complex roofs with dormers use 20–25%.
How much does a metal roof weigh vs asphalt?▾
Architectural asphalt shingles weigh ~235–300 lbs per square. Standing seam metal weighs ~50–75 lbs per square — roughly 4× lighter. This matters for structural loading; older homes may need a framing check before adding heavy tile (900–1,200 lbs/square).
Materials covered
This calculator covers 11 materials across 5 categories. All cost data sourced from RSMeans Construction Cost Data 2024.