Free Roofing Calculator

How to Use This Roofing Calculator

This calculator estimates your roofing materials and costs. Contractors use it for job bids. Homeowners use it for DIY projects. It follows industry-standard formulas.

Step 1: Measure Your Roof Dimensions

Start by measuring your roof's length and width. For a simple gable roof, measure your home's footprint. Complex roofs need section-by-section measuring. Break hip, gambrel, or mansard roofs into smaller parts. Calculate each section separately.

Pro Tip: Don't want to climb your roof? Measure from the ground instead. Use a tape measure and basic geometry. Measure your home's width first. Then add the overhang (typically 12-24 inches per side).

Step 2: Determine Your Roof Pitch

Roof pitch matters for accurate calculations. Pitch is a ratio of rise over run. A 6:12 pitch means 6 inches of rise for every 12 inches horizontal.

Common residential roof pitches:

• 4:12 to 6:12 - Most common for standard homes
• 7:12 to 9:12 - Steeper roofs, common in snowy areas
• 10:12 and above - Very steep, Victorian or Gothic style
• 2:12 to 3:12 - Low-slope, may need special materials

You can measure pitch two ways. Buy a pitch gauge ($10-20 at hardware stores). Or use the "2-foot level method": Place a 2-foot level flat on the roof. Measure the vertical distance from the 12-inch mark to the roof surface. That number is your pitch.

Step 3: Select Your Roof Type

Different roof types need different amounts of materials:

• Gable Roof - The simplest type, shaped like an inverted "V". Requires the least materials.
• Hip Roof - Slopes on all four sides. Needs about 10% more materials due to extra ridges and hips.
• Gambrel Roof - Barn-style with two pitches per side. Requires about 15% more materials.
• Mansard Roof - French-style with four sides, two slopes each. The most complex. Needs up to 20% more materials.

Step 4: Choose Your Roofing Material

We support five common roofing materials. Each has different costs, lifespans, and installation needs:

Asphalt Shingles ($95-150/square)

The most popular choice in North America. About 80% of homes use them. Asphalt shingles are affordable and easy to install. They come in many colors. Lifespan: 15-30 years (3-tab vs. architectural).

Metal Roofing ($350-600/square)

Growing in popularity. Metal roofs last 40-70 years with low maintenance. They boost energy efficiency. Choose standing seam, corrugated, or metal shingle styles. Higher upfront cost but great long-term value.

Clay or Concrete Tile ($500-800/square)

Common in Mediterranean and Southwestern homes. Extremely durable at 50-100 years. Warning: tiles are heavy. Your roof may need reinforcement. Excellent for hot climates due to natural air flow.

Slate Tile ($900-1,500/square)

The premium choice. Natural stone lasts 75-200 years. The most expensive option but unmatched in beauty and durability. Very heavy. Get a structural assessment first.

Wood Shakes ($450-700/square)

Cedar or redwood shakes offer rustic charm. Lifespan: 25-30 years with proper care. Popular in mountain and coastal areas. Check local codes first. Some fire-prone areas restrict wood roofing.

Understanding Roofing Squares

Roofing materials sell by the "square." One square equals 100 square feet. This standard makes ordering simple. A 2,000 sq ft roof equals 20 squares.

Important: Your roof area is larger than your home's footprint. Pitch adds area. A 6:12 pitch adds about 12% more area. A 12:12 pitch (45 degrees) adds 41% more.

Roof Pitch Multiplier Table

Use this table to convert your building's footprint area to actual roof area based on pitch:

Formula: Roof Area = Building Footprint × Pitch Multiplier

Waste Factor: Why You Need Extra Materials

Pros always order 10-20% extra materials. This waste factor covers:

• Cutting waste around chimneys, vents, valleys, and ridges
• Damaged or defective materials
• Future repairs (matching old materials is hard)
• Complex roof features needing more cuts

Recommended waste factors:

• Simple gable roof: 10%
• Hip roof with few features: 12-15%
• Complex roof with valleys and dormers: 15-20%

Cost Breakdown: Materials vs. Labor

This calculator shows material and labor costs separately. Here's the breakdown:

Material costs include shingles, underlayment, nails, ridge cap, and flashing. They make up about 40% of total cost.

Labor costs vary by region, complexity, and material type. Metal and tile roofs need special skills. They cost more to install than asphalt. Labor is about 60% of total cost.

When to Replace Your Roof

Replacing your roof on time saves thousands in water damage. Watch for these warning signs:

• Shingles curling, cracking, or losing granules
• Missing shingles after storms
• Daylight showing through roof boards in attic
• Water stains on ceilings or walls
• Roof age past material lifespan
• Sagging roof deck

DIY vs. Professional Installation

Roofing is dangerous work. OSHA reports that roof falls cause 30% of construction deaths. Think carefully before DIY.

Hire a pro if:

• Your pitch exceeds 6:12 (too steep for safe DIY)
• Your roof is over 2 stories high
• You're installing tile, slate, or metal
• Your area requires permits and inspections
• You need warranty coverage (DIY often voids it)

Get Free Quotes from Local Contractors

After you calculate materials, get quotes from licensed contractors. We suggest 3-4 quotes to compare prices, timelines, and warranties. Use our free service to find pre-screened pros in your area. No obligation. No fees.