Roof area & materials calculator
Calculate roof area, shingle bundles, and sheathing sheets from building dimensions and pitch.
Drop calc results into projects and quotes, invoice through your own Stripe, get paid. Built by a contractor.
Try TradeMaster Pro →How to Estimate Roofing Materials
Roofing materials are sold in squares — one square covers 100 square feet. Shingles come 3 bundles per square. To estimate, calculate the total sloped roof area and divide by 100.
The slope factor converts flat (plan-view) area to actual sloped area. A 6/12 pitch has a slope factor of 1.118 — meaning the actual roof surface is about 12% larger than the building footprint.
Waste Factors
- Gable roofs: 10% waste is typical — mostly from starter course and ridge cuts
- Hip roofs: 15% waste due to angled cuts along hip lines and more starter courses
- Complex roofs with valleys, dormers, or multiple planes may need 20%+ waste factor
Roofing materials are sold by the square, which covers 100 square feet. Most architectural shingles come in bundles of 3 per square. To estimate materials from the ground, measure the building footprint area and multiply by the slope factor for your pitch: 4/12 = 1.054, 6/12 = 1.118, 8/12 = 1.202, 12/12 = 1.414. This gives you the actual sloped roof area without climbing up there.
FAQ
How many bundles of shingles per square?
Most architectural shingles require 3 bundles per square (100 sq ft). A 2,000 square foot roof would need about 60 bundles, plus 10% extra for waste. Three-tab shingles also come 3 bundles per square, but some heavy architectural lines may require 4.
How do I measure a roof from the ground?
Measure the building footprint (length x width), then multiply by the slope factor for your roof pitch. Common slope factors: 4/12 = 1.054, 6/12 = 1.118, 8/12 = 1.202, 12/12 = 1.414. Add 10-15% extra for hip and valley waste. For complex roofs, consider an EagleView or similar aerial measurement report.
How much underlayment and starter strip do I need?
Synthetic underlayment comes in rolls covering roughly 1,000 square feet each. Starter strip shingles are sold per 100 linear feet — measure the total perimeter (eaves plus rakes) to determine how many bundles you need.