Home Addition Cost Calculator
Last updated: July 2026
Estimate a home-addition project budget from square footage, construction, design, permits, utility work and contingency.
Estimated home-addition project cost
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- Base construction estimate: —
- Professional, permit and utility costs: —
- Estimated contingency: —
- Estimated cost per added square foot: —
On this page
Quick summary: Estimate a home-addition project budget from square footage, construction, design, permits, utility work and contingency. Enter the requested values, calculate, review the result, and compare more than one realistic scenario before making a decision.
Read the complete guide
What this calculator estimates
Estimate a home-addition project budget from square footage, construction, design, permits, utility work and contingency. It is designed for fast planning and comparison in the United States. The output is an estimate, not a binding quote, approval, tax determination, insurance offer, legal conclusion, medical recommendation or professional advice.
How to use it
Enter the requested values using a single consistent time period and currency. Select Calculate, review the headline result and supporting figures, then change one assumption at a time to compare another scenario.
How the calculation works
Square footage is multiplied by the entered base construction cost, then design, permits and utility work are added. The contingency is applied to the subtotal.
Important limitations
Structural conditions, finishes, location, labor, demolition, foundation, weather, financing, code upgrades and contractor pricing vary.
Frequently asked questions
Is the result exact?
No. It is a planning estimate based on the assumptions entered.
Can I compare different scenarios?
Yes. Change one input at a time so you can see which assumption changes the result.
Does the calculator store my inputs?
The calculation runs in the browser and does not require an account. Avoid entering unnecessary confidential information.