Roofing Calculator
Calculate roofing squares, bundles of shingles, and total surface area based on building footprint and pitch factors. Professional material ordering.
Roofing Squares
1 Square = 100 ft²
Shingle Bundles
3 Bundles / Square
Waste Allowance
Add 10% for gables, 15% for hips and valleys.
The Roofing "Square"
In the roofing industry, a "Square" is the standard unit of measurement. One square covers exactly 100 square feet of roof surface. Shingles are typically sold in bundles, with three bundles required to cover one full square.
Pitch & Slope Dynamics
Pitch refers to the vertical rise of the roof for every 12 inches of horizontal run. A steeper roof has a larger surface area than a flat one, even if they share the same building footprint. This calculator uses professional "pitch multipliers" to convert ground area into true roof surface area.
Estimation Equation
Volume & Area Logic
Squares = (Footprint Area × Pitch Multiplier) ÷ 100
Multiply Squares by 3 to find your total Shingle Bundle requirement.
Material Check
- Standard 3-Tab shingles: 3 bundles/square
- Heavy Architectural: 4+ bundles/square
- Roofing Felt: 4 squares per roll (standard)
- Ice & Water Shield: 2 squares per roll
Waste Allowance
Always order extra material. A standard gable roof requires an additional 10% for the starter course and ridge caps. Complex roofs with hips, valleys, and dormers require 15% to 20% extra due to the amount of cutting involved.
Pitch Multiplier Reference
Pitch (Rise/12") Multiplier Description 3/12 1.031 Low slope 6/12 1.118 Standard residential 8/12 1.202 Steep residential 12/12 1.414 45-degree angle Frequently Asked Questions