Roof Square Footage Calculator
Calculate total roof square footage from building dimensions and pitch. Includes per-side area for gable roofs.
Formula & Explanation
This calculator combines two steps: 1. Calculate building footprint: Footprint = Length × Width 2. Apply pitch adjustment: Roof Area = Footprint × [1 / cos(pitch angle)] For a gable roof, the area is divided equally between two sides: Per-Side Area = Total Roof Area ÷ 2 Example: 40 ft × 25 ft building with 6:12 pitch - Footprint = 40 × 25 = 1000 sq ft - Pitch adjustment factor = 1.118 - Total roof area = 1000 × 1.118 = 1118 sq ft - Each side = 1118 ÷ 2 = 559 sq ft
Assumptions
- •Building footprint is measured as horizontal floor plan
- •Calculation assumes simple rectangular building with uniform gable roof
- •Does not account for complex roof shapes, overhangs, hips, valleys, or dormers
- •Per-side area assumes equal pitch on both sides
Example Calculation
A 40×25 ft building (1000 sq ft) with 6:12 pitch has 1118 sq ft total roof (559 sq ft per side).
Inputs
Results
Roof Areas for Common Building Sizes (6:12 pitch)
| size | footprint | roofArea |
|---|---|---|
| 30×20 | 600 sq ft | 671 sq ft |
| 40×25 | 1000 sq ft | 1118 sq ft |
| 50×30 | 1500 sq ft | 1677 sq ft |
| 60×40 | 2400 sq ft | 2683 sq ft |
Frequently Asked Questions
Related Calculators
Roof Area Calculator
Calculate total roof surface area from building footprint and pitch. Essential for material estimation.
Roofing Squares Calculator
Convert roof square footage to roofing squares. One roofing square covers 100 square feet of roof.
Roof Pitch Calculator
Calculate roof pitch, angle, and slope percentage from rise and run measurements.
Roof Shingle Calculator
Calculate the number of shingles and bundles needed for your roof. Includes waste factor adjustment.
Roofing Material Calculator
Calculate total roofing material costs including shingles, underlayment, and drip edge.