Home Addition Cost Calculator — Estimate Cost Per Square Foot [2026]
Estimate home addition cost by square footage, finish level, structural complexity, and fixed extras. See realistic low and high budget ranges instantly.
Quick Presets
Estimated Cost Range
Estimator Notes
- Use fixed extras for design, permits, utility tie-ins, HVAC expansion, or premium finishes.
- Large structural additions should always be checked against local quotes and financing limits.
What is Home Addition Cost Calculator?
How to Use Home Addition Cost Calculator
Enter the planned addition size in square feet, select the project complexity, and review the low and high installed cost per square foot. Add design, permitting, utility tie-ins, and finish upgrades in the extra cost fields if needed. The calculator returns a low estimate, high estimate, and a recommended working budget.
How Home Addition Cost Calculator Works
Common Use Cases
- Budgeting for a bedroom, office, family room, or master suite addition
- Comparing single-story additions with second-story or structural additions
- Estimating whether a home addition fits within financing limits before meeting a contractor
- Planning permit, design, and utility hookup costs on top of build cost
- Deciding between remodeling existing space and adding new square footage
Frequently Asked Questions
What is the average cost per square foot for a home addition?▼
Costs vary widely by region and finish level, but many home additions fall into a broad range from roughly $140 to $300+ per square foot before major structural surprises or premium finishes.
What drives the cost of a home addition the most?▼
Bathrooms, kitchens, second-story work, foundation changes, utility relocation, and structural engineering requirements often have the biggest cost impact.
Should I add contingency to a home addition budget?▼
Yes. Home additions regularly uncover hidden structural, electrical, or plumbing issues. A contingency buffer of 10% to 20% is common for early planning.
Can this replace a builder quote?▼
No. It is a planning calculator, not a formal quote. Use it to set expectations and compare scenarios before getting bids from licensed contractors.
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