Calculate roofing area, squares, number of shingles/sheets, underlayment and total cost. Supports gable, hip, shed and flat roofs with pitch factor adjustment. Works for any material.
🏠 Roofing Calculator
Roof Type
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Roofing Area
📋 Roofing Material Breakdown
📐 Roof Pitch Reference Guide
Pitch
Angle
Factor
Category
Suitable Materials
Pitch Factor Explained: A pitch factor of 1.118 means the actual roof surface area is 11.8% more than the footprint area. Calculated as: √(1 + (rise/run)²). This is why you always need more material than just the floor plan area.
📐 Roofing Calculations Explained
Roof Area from Footprint
Pitch Factor = √(1 + (Rise/Run)²)
Rise = vertical inches per 12 inches of run
Gable Roof Area:
Total = (Length + 2×Overhang) × (Width + 2×Overhang)
× Pitch Factor × 2 sides
Hip Roof Area:
Total ≈ Footprint × Pitch Factor × 1.05 (extra for hips)
Shed Roof Area:
Total = (Length + 2×Overhang) × (Width + 2×Overhang)
× Pitch Factor × 1 side
Flat Roof Area:
Total = Footprint area (no pitch factor needed)
Roofing Squares
1 Roofing Square = 100 square feet = 9.29 m²
Number of Squares = Total Roof Area (ft²) / 100
= Total Roof Area (m²) / 9.29
With wastage:
Order Squares = Squares × (1 + Wastage%)
Example: 10m × 8m gable, 5/12 pitch, 0.3m overhang
Footprint L = 10 + 0.6 = 10.6m
Footprint W = 8 + 0.6 = 8.6m
Roof area = 10.6 × 8.6 × 1.083 × 2 = 197.4 m²
Squares = 197.4 / 9.29 = 21.2 squares
10% waste = 23.3 squares → order 24 squares
Metal Sheet / GI Sheet Count
Effective sheet coverage = Sheet Width − Overlap
Sheets per row = Roof Width / Effective Width
Rows = Roof Length / (Sheet Length − Top Overlap)
Total sheets = Sheets per row × Rows (round up both)
Typical GI sheet: 0.9m wide, 2.5m long
Effective width = 0.9 − 0.15 = 0.75m
For 10m wide roof: Ceil(10/0.75) = 14 sheets/row
❓ Frequently Asked Questions
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