Roof Size Calculator
Estimate roof surface area including pitch, overhang and waste factor. Useful for ordering roofing materials and planning projects.
How it works
Enter the roof flat plan dimensions (length × width), choose units (meters or feet), set roof pitch (rise:run or degrees), add overhang and choose roof shape. The calculator multiplies the flat area by a pitch factor to get the actual surface area. A small shape modifier is applied for hip roofs.
Quick notes
- Pitch factor: For a pitched roof the sloped surface is longer than the flat projection. The pitch factor = √(1 + (rise/run)²) or 1 / cos(angle).
- Flat-equivalent area: The plan (flat) area = (length + 2×overhang) × (width + 2×overhang).
- Shape modifiers: Hip roofs typically add a small extra (defaults applied). Complex roofs require per-slope measurement.
Tip: Measure consistently (outside edge to outside edge). Include overhang if you want total material requirement. For very complex roofs, break into sections and sum results.
Disclaimer: This tool provides estimates for planning and material ordering. For structural or safety-critical work consult a professional roofer or architect.Why Roof Size Calculation Is Important
Knowing the exact roof size helps you estimate the correct amount of materials needed, including shingles, tiles, metal sheets, and insulation. Accurate measurements prevent material waste and unexpected expenses.
Benefits of Using a Roof Size Calculator
- Provides fast and accurate roof area results
- Reduces calculation errors
- Helps estimate material and labor costs
- Useful for homeowners, contractors, and builders
Who Should Use This Calculator
This calculator is ideal for homeowners planning roofing work, contractors preparing estimates, and construction professionals managing roofing projects.
Final Thought
A Roof Size Calculator simplifies roofing planning by providing accurate measurements. With the correct roof area, you can budget confidently, choose the right materials, and complete your roofing project efficiently.