Attic Conversion Cost Calculator
Estimate attic conversion costs including dormers, insulation, skylights, and optional bathroom addition.
Results
Visualization
How It Works
This calculator estimates the cost of converting an unfinished attic into livable space. Attic conversions can add a bedroom, office, or bonus room and typically cost $40-$100 per square foot depending on insulation and finish quality.
The Formula
Variables
- Sq Ft — Usable attic floor area with at least 7ft ceiling height
- Base Cost — $40 (basic), $65 (standard), or $100 (premium) per square foot
- Dormers — Shed or gable dormers at approximately $12,000 each
- Skylights — Installed skylights at approximately $2,500 each
- Bathroom — Optional bathroom addition at approximately $18,000
Worked Example
For a 500 sq ft attic with standard insulation, 1 dormer, 1 skylight, and no bathroom: (500 x $65) + $12,000 + $2,500 = $47,000.
Practical Tips
- Verify your attic floor joists can support the load of a finished room before starting any work.
- Dormers are expensive but dramatically increase usable floor area and headroom.
- Spray foam insulation costs more upfront but provides superior thermal performance in attic spaces.
- Check local codes for staircase requirements, which can reduce usable space on the floor below.
- Consider HVAC needs early since attics often require a separate mini-split or ductwork extension.
Frequently Asked Questions
How much does an attic conversion cost in 2026?
Most attic conversions cost $40,000-$80,000 for 400-600 sq ft of usable space, depending on dormers, bathroom, and finish level.
Do I need a permit for an attic conversion?
Yes, attic conversions require building permits in virtually all jurisdictions since they involve structural, electrical, and potentially plumbing work.
What is the minimum ceiling height for an attic room?
Most building codes require at least 7 feet of ceiling height over at least 50% of the usable floor area.
Are dormers necessary for an attic conversion?
Not always, but dormers add headroom, natural light, and ventilation. They are especially valuable in attics with steep roof pitches and limited standing room.
Does an attic conversion add home value?
Attic conversions typically recoup 60-75% of their cost and can add a bedroom to your home's listing, which significantly impacts resale value.