Roof Area Calculator
Calculate your total roof area from dimensions, pitch, and overhang
Calculate roof area from length, width, and pitch
Quick presets
ft
ft
Total Roof Area
1,754 sq ft
17.5 roofing squares • Pitch multiplier: 1.054
PRO
Professional Calculator
Calculate total area for complex roofs with multiple sections
ft
ft
Total Roof Area
1,389 sq ft
Sections
2
Total Squares
13.9
Cost Breakdown
Section 1: $1,054 (76%)
Section 2: $335 (24%)
Detailed Breakdown
Section 11,054 sq ft
Dimensions40 × 25 ft (footprint: 1,000 sq ft)
Pitch4/12 (×1.054)
Section 2335 sq ft
Dimensions20 × 15 ft (footprint: 300 sq ft)
Pitch6/12 (×1.118)
Total Roof Area1,389 sq ft
Total Squares13.9
Bundles (10% waste)46
How to Use This Calculator
From Dimensions: Enter your building's length and width in feet, select your roof pitch, and add your eave overhang. The calculator computes the true roof surface area adjusted for slope.
From Footprint: If you know your home's ground-floor square footage, enter it with your pitch. The calculator applies the pitch multiplier and adds overhang area.
The Formula
Roof Area = (Length + 2 × Overhang) × (Width + 2 × Overhang) × Pitch Multiplier
For a 50×30 ft building with 1 ft overhang and 4/12 pitch: (50 + 2) × (30 + 2) × 1.054 = 52 × 32 × 1.054 = 1,754 sq ft
For a 50×30 ft building with 1 ft overhang and 4/12 pitch: (50 + 2) × (30 + 2) × 1.054 = 52 × 32 × 1.054 = 1,754 sq ft
Example Calculation
Mike has a 50×30 ft single-story home in Ohio with a 4/12 pitch gable roof and 1-foot eave overhangs.
Footprint with overhangs: 52 × 32 = 1,664 sq ft Pitch-adjusted area: 1,664 × 1.054 = 1,754 sq ft In roofing squares: 17.5 squares Shingle bundles needed (10% waste): 17.5 × 3 × 1.10 = 58 bundles
Frequently Asked Questions
How do I calculate roof area from house square footage?
Multiply your home's footprint (ground floor area) by the pitch multiplier for your roof slope. A 1,500 sq ft footprint with a 4/12 pitch: 1,500 × 1.054 = 1,581 sq ft. Then add the overhang area.
What is a roofing square?
A roofing square is a unit of measurement equal to 100 square feet of roof area. When contractors say a roof is "17 squares," they mean 1,700 square feet. Shingles are priced and sold by the square.
Does roof pitch affect the roof area?
Yes. A steeper roof has more surface area than a flat roof over the same footprint. A 12/12 pitch (45 degrees) adds 41.4% more area than a flat roof. This is why you must account for pitch when ordering materials.