🏠 Roof Square Footage Calculator

Visual Guide

Roof Square Footage Calculator – Area, Squares, Bundles & Rolls

Use this free Roof Square Footage Calculator to estimate the size of your roof and translate it into roofing squares, shingle bundles, and underlayment rolls. Enter the house footprint, a uniform overhang, select the roof type (gable, hip, or shed), choose a pitch, and apply a waste factor. The tool also estimates ridge-cap length and drip-edge pieces so you can create a more complete materials list.

How to Use

1. Pick your Unit System, Roof Type, and Pitch.
2. Enter your house Length and Width (exterior wall-to-wall) and a uniform Overhang.
3. Set a Waste allowance (10% is a common starting point).
4. Adjust material coverage if needed: bundles per square, underlayment ft² per roll, ridge-cap LF per bundle, and drip-edge piece length.
5. Click Calculate to see roof area (ft²/m²), roofing squares, bundles, underlayment rolls, ridge/hip length, and drip-edge pieces.

What’s a “Roofing Square”?

One roofing square equals 100 square feet of roof surface. Most 3-tab and architectural shingles are sold as 3 bundles per square, but always check your specific product. Underlayment rolls commonly cover about 400 ft² (≈ 37 m²) effectively after overlaps.

Formulas & Assumptions

• Plan area (with overhangs): (L + 2e) × (W + 2e), where e is uniform overhang.
• Slope factor (common rafter): SF = √(1 + (rise/12)²) (independent of units).
• Roof surface area: A_roof = A_plan × SF. Then add waste: A × (1 + waste%).
• Squares: ft² ÷ 100. Bundles: squares × bundles/sq (round up).
• Underlayment rolls: area ÷ coverage per roll (round up).
• Linear footage: gable/shed eaves & rakes use the plan perimeter with overhangs; ridge length for gable is the house length; hip roofs use ridge ≈ L − W (≥0) and four hips.

Results are estimates. Roof framing, ventilation, underlayment classes, ice and water shield, and fastener schedules vary — always confirm against local code and manufacturer instructions.

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