Bedroom Addition Cost Calculator
Estimate the cost of adding a new bedroom to your home including foundation, framing, and optional en-suite bathroom and closet.
Results
Visualization
How It Works
This calculator estimates the cost of building a new bedroom addition onto your home. Room additions are one of the most significant home improvements, involving foundation work, framing, roofing, and utility extensions. Costs range from $100-$300 per square foot depending on quality and foundation type.
The Formula
Variables
- Sq Ft — Bedroom floor area in square feet
- Cost Per Sq Ft — $100 (budget), $180 (mid-range), or $300 (high-end)
- Foundation Mult — 1.0 (slab), 1.12 (crawl space), or 1.30 (full basement)
- Bathroom Cost — $12,000-$40,000 depending on finish level
- Closet Cost — $2,500-$9,000 for a walk-in closet
Worked Example
For a 200 sq ft bedroom on a slab foundation at mid-range quality with an en-suite and walk-in closet: (200 x $180 x 1.0) + $22,000 + $5,000 = $63,000.
Practical Tips
- Get at least three contractor bids and verify licenses, insurance, and recent references.
- A slab foundation is the least expensive option and works well in warm climates.
- Plan for HVAC extension costs, which may require upsizing your existing system.
- Check your property setback requirements before designing the addition footprint.
- An en-suite bathroom adds significant value but requires plumbing that increases cost substantially.
Frequently Asked Questions
How much does it cost to add a bedroom in 2026?
A bedroom addition typically costs $20,000-$75,000 for a basic 150-250 sq ft room, or $80,000-$150,000+ with an en-suite bathroom and premium finishes.
Do I need a permit to add a bedroom?
Yes. All room additions require building permits including structural, electrical, and plumbing permits. Working without permits can result in fines and problems at resale.
How long does it take to build a bedroom addition?
Most bedroom additions take 6-12 weeks from start to finish, depending on complexity, weather, and permit processing times.
Does a bedroom addition increase home value?
Adding a bedroom can increase home value by $30,000-$60,000 on average, with an ROI of 50-65% of the project cost.
What is the minimum size for a legal bedroom?
Most building codes require a minimum of 70 sq ft of floor area and at least 7 feet in each horizontal direction, plus a closet and egress window.