Shingle Calculator
Estimate shingle bundles and roofing squares including cutting waste.
Loading calculator…
What this tool does
Estimate shingle bundles and roofing squares including cutting waste. All roof planes have the same pitch; irregular extensions require separate sections. Bundles assume three per 100 square feet.
How to use the Shingle Calculator
- Enter or select length in ft.
- Enter or select width in ft.
- Enter or select roof pitch (rise per 12).
- Enter or select overhang on each edge in ft.
- Enter or select waste allowance (%).
- Read the calculated result; change any measurement to compare alternatives.
Formula
roof area=(length+2×overhang)×(width+2×overhang)×sqrt(1+(pitch/12)²); squares=area/100; bundles=ceil(area×(1+waste/100)/bundleCoverage)
- length
- Length (ft, before metric conversion)
- width
- Width (ft, before metric conversion)
- pitch
- Roof pitch (rise per 12)
- overhang
- Overhang on each edge (ft, before metric conversion)
- waste
- Waste allowance (%)
All roof planes have the same pitch; irregular extensions require separate sections. Bundles assume three per 100 square feet.
Worked example
For shingle calculator, the following measurements illustrate the exact method: Length: 20; Width: 10; Roof pitch (rise per 12): 6; Overhang on each edge: 1; Waste allowance (%): 10.
Inputs
- Length20 ft
- Width10 ft
- Roof pitch (rise per 12)6
- Overhang on each edge1 ft
- Waste allowance (%)10
Result
- Shingle bundles10
- Roofing squares3.25
- Area with waste324.68 sq ft
Results explained
- Shingle bundles
- Shingle bundles from the formula above. All roof planes have the same pitch; irregular extensions require separate sections. Bundles assume three per 100 square feet.
- Roofing squares
- Roofing squares from the formula above. All roof planes have the same pitch; irregular extensions require separate sections. Bundles assume three per 100 square feet.
- Area with waste
- Area with waste from the formula above, expressed in sqft before metric conversion. All roof planes have the same pitch; irregular extensions require separate sections. Bundles assume three per 100 square feet.
Frequently asked questions
Multiply horizontal footprint including overhangs by the slope factor; equal-pitch hip and gable roofs share this total area.
Use plan length/width, pitch and overhang.
Use 5–10% for simple layouts and 10–15% for diagonal cuts or complicated outlines; the allowance is editable.
Split the outline into rectangles or triangles and calculate each section separately. Do not count overlapping sections twice.
This is a purchasing estimate, not a structural design. Confirm measurements and local requirements before buying or building.