Room Addition Cost Calculator - 2025 Update

Planning a home or room addition? Whether you're building a garage, sunroom, second story, adding a bedroom, or expanding your living space, our free Room Addition Cost Calculator gives you an instant estimate. Just enter your square footage and project type to see real-time pricing for your location.

Use it to plan your budget, compare options, and feel confident before hiring a contractor.

Estimate Costs for Every Kind of Addition

  • For bedrooms, bathrooms, and bonus rooms

  • Add a new story to your property

  • Additional number of stories for your property

  • Add a patio, deck, sunroom or other

  • Home addition cost estimator by square footage

Diagram showing bedroom, bathroom, and second-story additions cost estimation and breakdown

Estimate the Cost of Room Additions

No signup. No hidden fees. Just a fast, simple tool to calculate the cost of any type of home renovation.

Main cost categories of your room addition

Room addition and renovation tool

  • This includes site survey, soil testing, excavation, grading, and other site-related work required for the addition

  • This includes pouring the foundation, installing footings, framing, roofing, and other structural work necessary for the addition

  • This includes siding, roofing, windows, doors, and other exterior finishes to match the existing house

  • This includes insulation, drywall, flooring, paint, and other finishes for the interior of the addition

  • This includes installing new heating, ventilation, and air conditioning systems

  • This includes work for lighting, outlets, and appliances

  • his includes installing new plumbing fixtures, piping, and connections for the addition

  • This includes decorative finishes, such as trim work, paint, flooring, and cabinetry, to complete the look of the addition

One-Story vs. Two-Story Costs vs. Sunrooms, Garages, and Master Suites vs. Other

The price of a home addition depends on:

  • Square footage
  • Type of addition (room, bathroom, second story, garage, etc.)
  • Location and local labor costs
  • Material quality and finish level
  • Permit fees and contractor costs

Check our renovation estimating guide

 FAQs

  • Room additions typically range from $120 to $250 per square foot, depending on location and materials.

  • Yes, second-story additions cost more—usually $200 to $400 per square foot—due to structural engineering and roofing modifications.

  • asic single-room additions with minimal plumbing and finishes are usually the most cost-effective.

  • Yes, most jurisdictions require building permits for room or home additions. Your contractor should factor this into your estimate.

  • Second-story additions often require structural reinforcements and cost more per square foot. Use the calculator to compare both scenarios instantly.

  • Yes, Remodelum supports different room types, including sunrooms, garages, and master suites.

  • Yes. You can estimate costs without signing up. Optionally, create a free account to save and compare estimates.

What type of renovation do you want to calculate?

Need to Track and Manage your Renovation?

Track expenses, record payments, store estimates & contractor information, calculate outstanding payments & overruns, and manage changes in scope—all in one place. Quick and Easy!

Room Addition Budget Tracker

Renovating for the first time?

Check Remodelum’s guide for first time renovations - Get tips and best practices for your home remodeling projects