Roofing Calculator
Calculate shingle bundles and roofing squares. Automatically adjusts for roof pitch and includes waste factor.
Roof Measurements
Measure house footprint, not actual roof surface
Standard 3-tab: 33.3 sq ft (3 bundles = 1 square)
Your Estimate
Bundles Required
0
shingle bundles
Area Breakdown
Understanding Roofing Terms
What is a "Square"?
In roofing, one square equals 100 square feet of roof surface. This is the standard unit for measuring and ordering roofing materials. A 1,500 sq ft roof = 15 squares.
What is Roof Pitch?
Pitch is expressed as rise/run. A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. Steeper pitches have more surface area than the footprint suggests.
Roofing Formula
Bundles = (Footprint x Pitch Multiplier x Waste) / Bundle Coverage
Pitch multiplier converts flat area to actual roof surface area.
Pitch Multiplier Reference
| Pitch | Multiplier | Description |
|---|---|---|
| 0/12 | 1.00 | Flat roof |
| 4/12 | 1.054 | Low slope |
| 6/12 | 1.12 | Standard residential |
| 8/12 | 1.20 | Moderate slope |
| 10/12 | 1.30 | Steep - safety gear needed |
| 12/12 | 1.41 | 45-degree angle |
Roofing Material Weights: Structural Considerations
Your roof structure must support the weight of roofing materials. Before changing materials (especially from asphalt to tile or slate), consult a structural engineer.
| Material | Weight (per square) | Lifespan |
|---|---|---|
| 3-Tab Asphalt Shingles | 200-250 lbs | 15-20 years |
| Architectural Shingles | 300-400 lbs | 25-30 years |
| Metal Roofing | 100-150 lbs | 40-70 years |
| Wood Shakes | 350-400 lbs | 20-40 years |
| Clay Tile | 900-1200 lbs | 50-100 years |
| Slate | 1000-1500 lbs | 75-200 years |
Important: Tear-Off vs. Overlay
Most building codes allow a maximum of two layers of shingles. Adding a layer (overlay) saves labor but adds weight and may void warranties. Tear-off to the deck is recommended for best results.
Additional Roofing Materials to Order
Underlayment
Felt or synthetic membrane under shingles.
- 15 lb felt: Economy option
- 30 lb felt: More durable
- Synthetic: Premium, tear-resistant
Ice & Water Shield
Self-adhering membrane for vulnerable areas.
- Required at eaves in cold climates
- Around all penetrations (vents, skylights)
- In valleys where slopes meet
Drip Edge
Metal flashing at roof edges.
- Measure perimeter of roof
- Sold in 10-foot lengths
- Available in various colors
Ridge Cap
Special shingles for the peak.
- Measure linear feet of ridge and hips
- ~35 linear feet per bundle
- Match to field shingle color
Frequently Asked Questions
How do I measure my roof from the ground?
Measure your house footprint (length x width), then multiply by the pitch factor. For complex roofs, break into rectangles and triangles, calculate each section, and add them together.
What's the difference between 3-tab and architectural shingles?
3-tab shingles are flat with cutouts creating a uniform pattern. Architectural (dimensional) shingles are thicker with a layered, textured appearance. Architectural shingles cost more but last 10+ years longer.
Should I DIY my roof?
Roofing is dangerous work. Falls from roofs cause thousands of injuries yearly. For steep pitches (8/12 or higher), we recommend hiring professionals with proper safety equipment.