Room Addition Calculator

Calculate room addition costs including foundation, framing, roofing, and finishes. Get accurate estimates for bedroom, bathroom, family room, and suite additions.

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🏠For Homeowners: Get a quick cost range with just a few measurements. Perfect for budgeting and comparing contractor quotes.

Type of room being added
sq ft
Total square footage of the addition
Second story costs more due to structural requirements
Foundation type affects base cost significantly
Quality of finishes affects overall cost
Enter your ZIP code to adjust costs for your region
Assumptions & Sources

Assumptions

  • Foundation costs: Based on typical residential foundation requirements for your region.
  • Story multiplier: Second story additions cost 35% more due to structural requirements.
  • Finish level: Basic (builder-grade), Standard (mid-range), Premium (high-end), Luxury (custom).
  • Timeline: Based on typical crew size and permit processing times.
  • Permits: Assumes standard residential permit fees in your area.

Data Sources

  • RSMeans Construction Cost Data 2025
  • HomeAdvisor True Cost Guide 2024
  • Remodeling Magazine Cost vs. Value Report 2024
  • National Association of Home Builders (NAHB)

Last updated: January 2026

* Budget Planning Guide: These budget ranges are based on generalized industry data and may vary based on location, material quality, and local market conditions. Always obtain written bids from licensed contractors before making financial decisions.