Home Addition Cost Calculator

Estimate the cost of building a new room or extension onto your home. Calculate total construction expenses based on square footage and finish quality.

Addition size sq ft The total new floor area Please enter a positive number

Addition type Different rooms require different base costs (plumbing, cabinetry, etc.)

Finish quality Quality of flooring, fixtures, and exterior matching

Calculation Results

Estimated total cost

— USD

Estimate includes labor, materials, and basic site prep.

How to use this cost calculator

Enter the square footage

Input the total area of your planned home addition. The national average size for a room addition is around 400 square feet.

Select the room type

Choose what type of space you are building. Kitchens and bathrooms cost significantly more due to plumbing, electrical, and cabinetry requirements.

Choose your finish quality

Select whether you plan to use standard builder-grade materials, custom mid-range options, or luxury high-end finishes.

Home Addition Estimates by Room Type

Addition Size	Room Type	Finish Quality	Estimated Total Cost
200 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$30,000
200 sq ft	Living Room / Bedroom	Premium (Custom)	$45,000
200 sq ft	Kitchen Expansion	Standard (Builder Grade)	$50,000
200 sq ft	Kitchen Expansion	Premium (Custom)	$75,000
200 sq ft	Bathroom Addition	Standard (Builder Grade)	$60,000
200 sq ft	Bathroom Addition	Premium (Custom)	$90,000
400 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$60,000
400 sq ft	Living Room / Bedroom	Premium (Custom)	$90,000
400 sq ft	Kitchen Expansion	Standard (Builder Grade)	$1,00,000
400 sq ft	Kitchen Expansion	Premium (Custom)	$1,50,000
400 sq ft	Bathroom Addition	Standard (Builder Grade)	$1,20,000
400 sq ft	Bathroom Addition	Premium (Custom)	$1,80,000
600 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$90,000
600 sq ft	Living Room / Bedroom	Premium (Custom)	$1,35,000
600 sq ft	Kitchen Expansion	Standard (Builder Grade)	$1,50,000
600 sq ft	Kitchen Expansion	Premium (Custom)	$2,25,000
600 sq ft	Bathroom Addition	Standard (Builder Grade)	$1,80,000
600 sq ft	Bathroom Addition	Premium (Custom)	$2,70,000
800 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$1,20,000
800 sq ft	Living Room / Bedroom	Premium (Custom)	$1,80,000
800 sq ft	Kitchen Expansion	Standard (Builder Grade)	$2,00,000
800 sq ft	Kitchen Expansion	Premium (Custom)	$3,00,000
800 sq ft	Bathroom Addition	Standard (Builder Grade)	$2,40,000
800 sq ft	Bathroom Addition	Premium (Custom)	$3,60,000
1000 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$1,50,000
1000 sq ft	Living Room / Bedroom	Premium (Custom)	$2,25,000
1000 sq ft	Kitchen Expansion	Standard (Builder Grade)	$2,50,000
1000 sq ft	Kitchen Expansion	Premium (Custom)	$3,75,000
1000 sq ft	Bathroom Addition	Standard (Builder Grade)	$3,00,000
1000 sq ft	Bathroom Addition	Premium (Custom)	$4,50,000
1500 sq ft	Living Room / Bedroom	Standard (Builder Grade)	$2,25,000
1500 sq ft	Living Room / Bedroom	Premium (Custom)	$3,37,500
1500 sq ft	Kitchen Expansion	Standard (Builder Grade)	$3,75,000
1500 sq ft	Kitchen Expansion	Premium (Custom)	$5,62,500
1500 sq ft	Bathroom Addition	Standard (Builder Grade)	$4,50,000
1500 sq ft	Bathroom Addition	Premium (Custom)	$6,75,000

Frequently asked questions

How much does a home addition cost per square foot?

On average, a home addition costs between $150 and $300 per square foot, depending heavily on the room type, materials used, and your local labor rates. Basic living rooms fall on the lower end, while wet rooms like bathrooms and kitchens sit on the higher end.

What is the most expensive type of home addition?

Kitchens and bathrooms are the most expensive additions per square foot. They require extensive electrical work, complex plumbing lines, cabinetry, countertops, and specialized flooring, all of which drive up both material and labor costs.

Does building a second story cost more than building out?

Usually, yes. Building up requires removing the existing roof, reinforcing the foundation and load-bearing walls to hold the extra weight, and adding a staircase. However, if your lot size is small or yard space is at a premium, building a second story might be your only option.

Are architectural fees and building permits included in this cost?

This calculator provides a baseline estimate for labor and construction materials. It does not factor in "soft costs" such as architectural plans, engineering stamps, municipal building permits, or increased property taxes, which typically add 10-15% to the final budget.

About this calculator

This home addition cost calculator helps homeowners and real estate investors generate quick budgetary estimates for property extensions. Whether you are adding a master suite, expanding a kitchen, or building a sunroom, understanding baseline construction costs is the first step before consulting with a general contractor.

The estimate uses the following calculation method based on national averages:

Cost per Sq Ft = Base Room Rate × Quality Multiplier
Total Estimated Cost = Square Footage × Cost per Sq Ft

(Materials are estimated at ~55% of total cost; Labor at ~45%)

Keep in mind that actual costs fluctuate drastically based on regional labor rates, supply chain availability, and specific site conditions (such as the need for extensive excavation or foundation work). We recommend using this tool for initial financial planning and obtaining at least three local contractor bids before starting your project.