Roofing Shingle & Square Footage Calculator
Estimate the number of squares and bundles required for your roofing project based on pitch and waste factor.
Flat (0/12)
Low Pitch (2/12)
Standard (4/12)
Medium (6/12)
Steep (8/12)
Very Steep (10/12)
Extreme (12/12)
5% (Simple Gable)
10% (Standard Hip)
15% (Complex / Valleys)
20% (Very Complex)
Estimation Results
Base Flat Area:
0
Actual Surface Area (with Pitch):
0
Total Squares Needed (100 sq ft each):
0
Total Bundles to Order:
0
How to Calculate Roofing Shingles
When planning a roofing project, understanding the terminology is the first step. Professional roofers measure area in "Squares." One roofing square is equal to 100 square feet of roof surface.
The Mathematical Formula
To calculate your roof's area accurately, you cannot simply use the footprint of the house. You must account for the slope (pitch). The formula used by this calculator is:
- Step 1: Length × Width = Base Area.
- Step 2: Base Area × Pitch Multiplier = Actual Surface Area.
- Step 3: Surface Area × Waste Factor = Total Material Needed.
- Step 4: Total Material / 100 = Total Squares.
Realistic Example:
Imagine a standard ranch home with a footprint of 40ft by 30ft and a 6/12 pitch.
1. Base Area: 1,200 sq ft.
2. Pitch Adjustment (6/12 = 1.118): 1,200 × 1.118 = 1,341.6 sq ft.
3. Waste Factor (10%): 1,341.6 × 1.10 = 1,475.76 sq ft.
4. Result: 14.76 Squares. Since shingles come in bundles (usually 3 per square), you would order 45 bundles.
Imagine a standard ranch home with a footprint of 40ft by 30ft and a 6/12 pitch.
1. Base Area: 1,200 sq ft.
2. Pitch Adjustment (6/12 = 1.118): 1,200 × 1.118 = 1,341.6 sq ft.
3. Waste Factor (10%): 1,341.6 × 1.10 = 1,475.76 sq ft.
4. Result: 14.76 Squares. Since shingles come in bundles (usually 3 per square), you would order 45 bundles.
Why the Waste Factor is Critical
Every roof project involves cutting shingles to fit edges, valleys, and ridges. A simple gable roof might only require a 5% waste factor. However, if your roof has multiple dormers, valleys, or a hip design, you should use a 15% or even 20% waste factor to ensure you don't run out of material mid-job.
How many bundles are in a square?
In almost all cases for standard asphalt architectural shingles, there are 3 bundles per square. If you are using heavy-duty designer shingles, there may be 4 or 5 bundles per square, so always check the manufacturer's packaging.