Home Addition Cost Calculator – Estimate Room & Second Story Additions

Planning a home addition? Use our free Home Addition Cost Calculator to estimate the cost of building a room, sunroom, or second story. Whether you're expanding your kitchen, adding a new bedroom, or going vertical, get real-time pricing based on your location and square footage.

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

Remodelum's addition calculator screenshot

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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

Planning a Room Addition?

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?

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Room Addition Budget Tracker