Roofing Calculator
Estimate roofing materials before getting quotes. Enter roof footprint, pitch, and material type to get roofing squares, shingle bundles, felt rolls, and a cost range.
How to use Roofing Calculator
The roofing calculator estimates the number of shingles (squares), underlayment and ridge cap needed to reroof a home. Enter the roof footprint area and pitch, and the tool calculates actual roof area, number of bundles, waste factor for valleys and hips, and an estimated material cost.
- Enter the house footprint length and width.
- Enter the roof pitch (rise over run, e.g. 6/12 for a 6" rise per 12" run).
- Add number of dormers, valleys and hips if applicable.
- Set a waste factor (10–15%).
- Review actual roof area in squares, bundle count and estimated materials.
Your data never leaves your device — 100% private processing.
Roof pitch, area and squares
One roofing square = 100 sq ft of roof surface. Actual roof area > footprint because of slope. Pitch multiplier for a 6/12 pitch ≈ 1.118; for 8/12 ≈ 1.202; for 12/12 ≈ 1.414. Actual area = footprint area × pitch multiplier. Standard three-tab shingles: 3 bundles per square. Architectural (dimensional) shingles: 3–4 bundles per square. Always add 10–15% for waste, hips, ridges and valleys.
| Pitch (rise/run) | Pitch multiplier | Slope category |
|---|---|---|
| 2/12 | 1.014 | Low pitch |
| 4/12 | 1.054 | Low-moderate |
| 6/12 | 1.118 | Moderate (most common) |
| 8/12 | 1.202 | Moderate-steep |
| 12/12 | 1.414 | Steep (45°) |
Shingle types and lifespan
Three-tab asphalt shingles: 20–25 year lifespan, 60–80 mph wind rating, cheapest option. Architectural (dimensional) shingles: 30–50 year lifespan, 110–130 mph wind rating, most popular. Premium designer shingles: 50+ year lifespan, simulate slate or wood shake appearance. Metal roofing: 40–70 year lifespan, most durable but 2–4× the cost of asphalt. Choose based on local climate, wind and budget.
Glossary
- Roofing square
- 100 square feet of roof surface — the standard roofing material unit.
- Bundle
- One-third of a roofing square of shingles; three bundles = one square.
- Pitch
- Roof slope expressed as rise over a 12-inch horizontal run (e.g. 6/12).
- Valley
- The V-shaped junction where two roof planes meet; requires extra flashing and shingles.
Related reading
Frequently Asked Questions
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Why use Roofing Calculator?
- Accurate material estimates reduce waste and over-ordering
- Supports both metric and imperial measurements
- Covers common materials: concrete, lumber, flooring, paint
- Results include waste factor buffers for professional accuracy
Common use cases
- Calculate concrete needed for a driveway
- Estimate flooring tiles for a room renovation
- Work out paint quantity for interior walls
- Calculate lumber needs for a deck project
- Estimate roofing material for a pitched roof
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