Home Addition Cost Calculator
A home addition cost calculator estimates the price of a room addition by multiplying the addition's square footage by your price per square foot for finished construction. Additions are priced per finished square foot, which bundles foundation, framing, finishes and systems. Enter your addition size and price per square foot below for an estimate.
finished construction price per sqft, user-entered; wide range by finish level.
Enter the dimensions to estimate the cost.
Estimate only. Prices vary by region, supplier, material grade and labor. Enter your own local price; this site never quotes prices.
How Much Does a Home Addition Cost?
A home addition costs its square footage times your price per finished square foot, a figure that bundles the foundation, framing, roofing, siding, windows, interior finishes and mechanical systems. The price per square foot varies enormously with the finish level and whether the addition includes a kitchen or bathroom, which add plumbing and high-cost finishes. The calculator estimates from your price per square foot, so use a local rate for your addition type.
Why Do Additions Cost So Much per Square Foot?
Additions cost a lot per square foot because they are complete construction: a new foundation, framing, roof, exterior and interior, plus tying into the existing home's structure and systems. Bathrooms and kitchens cost the most per square foot due to plumbing, electrical and finishes. A simple bedroom addition costs less per foot than a kitchen extension. The calculator uses your price, so match it to the room type.
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Frequently asked questions
- How much does a home addition cost?
- It is the square footage times your price per finished square foot, bundling foundation, framing, finishes and systems. Kitchens and baths cost more per foot. Enter your local price.
- Why are home additions expensive per square foot?
- They are complete construction (foundation, framing, roof, finishes, systems) tied into the existing house. Kitchens and baths cost most due to plumbing and finishes.