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How To Calculate Roofing Square Footage

November 30, 2025

2 min read

To calculate roofing square footage, you need to measure the length and width of your roof, then multiply those numbers together. Most roofs are measured in squares, which equals 100 square feet. The average U.S. roof size is 2,647 square feet or 26.47 squares, according to the National Association of Home Builders. Knowing your exact roof size helps you get accurate repair and replacement costs. This measurement is the first step before hiring a roofer or buying materials.

What Is a Roofing Square?

A roofing square is simply 100 square feet. Roofers use this unit instead of square feet because it makes math easier. If your roof is 2,000 square feet, that equals 20 squares.

Contractors charge by the square. According to RubyHome (2025), roof installation costs range from $4 to $40 per square foot, or $400 to $4,000 per square. For a 1,700 square foot roof, that means a total cost between $6,800 and $68,000.

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How to Measure Your Roof Size

Start by measuring your home’s length and width from the ground. Use a measuring tape or check your home’s blueprints. Multiply length times width to get the total square footage.

Example: If your home is 40 feet long and 30 feet wide, that equals 1,200 square feet. But wait. Your roof may be larger than your home’s footprint because of roof pitch and overhangs. A steeper roof covers more area. This is why professional measurements are important.

If you feel unsafe on a ladder, hire a roofer to measure instead.

Common Roof Material Costs Per Square

Different materials cost different amounts. According to RubyHome (2025), here are typical costs for popular roofing materials:

Material TypeCost Per Square FootCost Per Square (100 sq ft)
Basic asphalt shingles$4.25 to $4.95$425 to $495
Architectural asphalt shingles$4.50 to $8.25$450 to $825
Metal roofing$5.50 to $17.05$550 to $1,705
Slate tiles$12.00 to $22.00$1,200 to $2,200

Why Size Matters for Your Budget

The average roof replacement cost is $9,526, according to RubyHome (2025). But costs range from $5,868 to $13,217 for most homes. Larger roofs cost more. A bigger measurement means more materials and more labor hours.

Asphalt shingles dominate about 80% of residential roofing projects in the U.S., according to RubyHome (2025). They are the cheapest option. Metal roofing holds about 10% of the market but lasts much longer. According to RubyHome (2025), metal roofs last 40 to 80 years, while asphalt shingles last only 20 to 30 years.

Get multiple quotes before deciding. Always measure twice to ensure accuracy.

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If you need help with your roof, reach out to a trusted roofing company for clear pricing and reliable service.