Roof Square Footage Calculator (Squares & Bundles) – Pitch + Waste

Q: How do I calculate roof squares from square footage?

One roofing square equals 100 square feet of roof surface. To get squares, divide roof area (ft²) by 100. If you’re using meters, convert to ft² or use the calculator’s squares output.

Q: What waste percentage should I use for a gable vs hip roof?

As a practical starting point, gable roofs often use 5–10% waste, while hip roofs commonly use 10–15% due to additional cuts and complexity. Always adjust for valleys, dormers, and product requirements.

Q: How many bundles are in a square?

Most asphalt shingles are packaged so 3 bundles cover 1 roofing square (100 ft²), but some products vary. Always verify the manufacturer’s coverage for your specific shingle.

Q: Does this include overhangs?

Yes. The calculator adds the selected uniform overhang to both length and width (L + 2e and W + 2e) before applying pitch and waste.

Q: Does underlayment coverage include overlaps?

Underlayment roll coverage is often quoted as a maximum area, but effective coverage can be lower due to overlaps and detailing. This calculator uses your entered roll coverage and rounds up; consider reducing coverage if you want to account for overlaps more conservatively.

Unit System

Roof Type

Pitch (rise / 12)

Slope factor: 1.118 (6/12)

Waste

Typical: gable 5–10%, hip 10–15%.

House Length (ft)

House Width (ft)

Overhang (in)

Uniform eave/rake overhang. Typical 8–16 in.

Bundles per Square

Most asphalt shingles are ~3 bundles per square; verify your product.

Underlayment Coverage (/roll)

ft² per roll (effective coverage can be lower with overlaps)

Ridge-Cap Coverage (/bundle)

Linear feet (≈ 10 m)

Drip-Edge Piece Length

Feet per piece (≈ 3 m)

Tip: Press Enter to calculate.

Visual Guide

Eaves Rakes Ridge Hips

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

Pick your Unit System, Roof Type, and Pitch.
Enter your house Length and Width (exterior wall-to-wall) and a uniform Overhang.
Set a Waste allowance (10% is a common starting point).
Adjust material coverage if needed: bundles per square, underlayment per roll, ridge-cap per bundle, and drip-edge piece length.
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.
Hip roof slope note (why hips differ): hip lines run diagonally in plan (45°), and their true sloped length increases with pitch. This calculator estimates hip lengths from diagonal plan geometry and applies a hip-specific slope factor.

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

Related Roofing Calculators

Roof Pitch Calculator Roof Truss Calculator Shingle Calculator All Roofing Calculators

Accuracy & Review

Reviewed by: Caleb Wright

Caleb validates our roofing calculators, reviewing shingle coverage assumptions, waste factor guidance, and practical measurement conventions. He focuses on real-world estimating so results align with typical ordering and installation practices.

Last updated: Feb 12, 2026

See: Methodology · Data Sources · Review Board

FAQ

How do I calculate roof squares from square footage?

A roofing square is 100 ft² of roof surface area. Divide your roof area (ft²) by 100 to get squares. This calculator provides squares automatically after applying pitch and waste.

What waste percentage should I use for a gable vs hip roof?

A common starting point is 5–10% waste for gable roofs and 10–15% for hip roofs. Increase waste for complex roofs (valleys, dormers, multiple sections) or when required by the manufacturer.

How many bundles are in a square?

Many asphalt shingle products are packaged so 3 bundles ≈ 1 square, but coverage can vary by shingle type and brand. Always confirm coverage on your product packaging or spec sheet.

Does this include overhangs?

Yes. The calculator adds your selected uniform overhang to both length and width (L + 2e and W + 2e) before applying pitch and waste.

Does underlayment coverage include overlaps?

Underlayment roll coverage is often listed as a maximum area, but effective coverage can be lower due to overlaps, starter strips, and detailing. If you want conservative estimates, reduce the “coverage per roll” value.

Important Estimate Disclaimer

Results are preliminary estimates only and do not replace professional roofing specifications. Material quantities may vary based on pitch complexity, waste factors, underlayment layers, and local code requirements.

Review our Methodology and Data Sources for calculation details.

Wind exposure, flashing requirements, and structural considerations may affect final material totals.