Attic Square Footage Calculator
Effective attic floor area accounting for sloped roof. Useful for insulation orders.
Result
Effective attic area
600 ft²
Full floor.
- Floor footprint600 ft²
- Effective factor1.00
- Effective area600 ft²
Step-by-step
- Area = 30 × 20 × 1 = 600 ft².
How to use this calculator
- Enter attic floor length and width.
- Pick whether kneewalls limit the usable area.
About this calculator
Attic square footage matters for insulation orders. Walkable attics (full floor): use the full footprint. Attics with kneewalls (where the roof slopes too low for full headroom): use ~70% of the floor area as effective.
Frequently asked
Approximation: roof slope cuts off the perimeter strip. Exact factor depends on roof pitch and ceiling height.
Related calculators
Floor Area Calculator
L × W = floor area in ft². For flooring orders, multiply by 1.10 (10% waste).
Square Footage Calculator (Rectangular)
Length × width = ft². The simplest area calc.
Wall Area for Paint Calculator
Perimeter × ceiling height − doors and windows = paintable area.
Plywood Sheet Count Calculator
Sheets = surface area / 32 ft² (standard 4×8 sheet) + waste.
Ceiling Area Calculator
Ceiling area = floor area (for flat ceilings).
Concrete Volume Calculator
Calculate cubic yards and cubic feet of concrete needed for a slab, footing, or pad — given length, width, and depth.