How many bundles of shingles in a square?

Standard 3-tab shingles come 3 bundles per square (100 sq ft). Architectural/dimensional shingles are heavier and often come 4-5 bundles per square. Always check the coverage listed on the bundle packaging for your specific product.

How do I calculate roof pitch for materials?

Measure the vertical rise per 12 inches of horizontal run. A 6/12 pitch rises 6 inches for every 12 inches horizontal. Multiply flat roof area by the pitch factor: 4/12=1.054, 6/12=1.118, 8/12=1.202, 10/12=1.302, 12/12=1.414.

How long do asphalt shingles last?

3-tab shingles last 15-20 years. Architectural shingles last 25-30 years. Premium architectural shingles can last 40-50 years. Actual lifespan depends on climate, ventilation, installation quality, and maintenance. Hot climates reduce shingle life.

Do I need to remove old shingles before re-roofing?

Most codes allow up to 2 layers of shingles. However, tear-off is recommended to inspect decking for damage, ensure proper installation, and maintain warranty coverage. Adding weight with multiple layers can stress roof structure.

How much does a new roof cost?

Average roof replacement costs $8,000-$15,000 for asphalt shingles on a typical home. Factors include roof size, pitch (steep = more labor), material choice, tear-off needs, and local labor rates. Get 3+ quotes for accurate pricing.

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Roofing Calculator

Calculate roofing squares for shingles, tiles, or metal

0 calculations

Last verified: February 2026Accuracy tested

Calculated in your browser — we never store your dataIncludes standard waste factors

Roof Length (ft)

Roof Width (ft)

Roof Pitch

Waste Factor (%)

Calculation Result

9.6 roofing squares

964 total sq ft (including pitch adjustment)

~29 bundles of shingles (3 per square)

Pitch: 6/12 with 15% waste factor

Sources & Methodology

Formula: Squares = (Roof Area × Pitch Factor) / 100

One roofing square = 100 square feet

Source: National Roofing Contractors Association guidelines

View full methodology & accuracy testing

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Estimate Your Project Cost

See full roof replacement costs with labor →

Roof Replacement Cost Guide on CostOnce.com

How to Use the Roofing Calculator

Calculate roofing squares, shingle bundles, and total coverage area. Our calculator accounts for roof pitch and waste factor to give you accurate material estimates. Start by measuring your roof's footprint using our square footage calculator.

Understanding Roof Pitch

Roof pitch is expressed as rise over run (e.g., 6/12 means 6 inches of rise per 12 inches of horizontal run). Steeper pitches require more material due to increased surface area. We apply the appropriate multiplier automatically.

Squares and Bundles

A roofing "square" covers 100 square feet. Most asphalt shingles require 3 bundles per square. Premium or architectural shingles may require 4-5 bundles per square.

Professional Advice

Roofing is complex and dangerous work. We recommend consulting with a licensed roofing contractor for accurate assessments, especially for:

Complex roof shapes with multiple valleys and hips
Steep roofs requiring special safety equipment
Re-roofing over existing shingles
Warranty and code compliance requirements

Related Home Exterior Calculators

Complete your home exterior project with our lumber calculator for fascia and soffits, insulation calculator for attic insulation, and paint calculator for trim. Use the loan calculator to finance major roof replacements.

Frequently Asked Questions

Measure roof length x width for each section, sum the areas, then divide by 100 (one square = 100 sq ft). Add 10-15% for waste and starter strips. A 30x40 foot roof = 1,200 sq ft = 12 squares + waste = order 14 squares.