Home Addition Cost Calculator

HOME PLANNING TOOL

Estimate construction expenses, additional project costs, contingency, and financing payments using your own budget assumptions.

1. Project details

Addition type

Added area Cost per area

Enter a local construction rate. The starting value is only an example and is not a location-specific quote.

Construction complexity

2. Construction costs

Materials percentage Labor percentage Site preparation and foundation Interior finishes and fixtures

Materials and labor percentages are used to show a breakdown of the base construction amount. Additional expenses are calculated separately.

3. Professional and approval costs

Architect and design fees Engineering and surveys Permits and inspections Demolition and removal Utility connections and changes

4. Additional expenses

Furniture and equipment Temporary accommodation Other project expenses Contingency reserve

A contingency reserve is an allowance for unexpected work, price changes, and project surprises. Select a percentage appropriate for your situation.

5. Financing estimate

Amount financed

Annual interest rate (%) Loan term (years)

The financing result is an illustrative principal-and-interest estimate. It does not include lender-specific fees, taxes, insurance, or approval requirements.

6. Affordability check

Monthly household income Existing monthly debt payments Target maximum debt-to-income ratio (%)

This check is educational and does not determine loan eligibility. Lenders may use different income, debt, credit, and underwriting requirements.

Estimated total project cost — Enter your details to calculate.

Base construction —

Additional expenses —

Contingency —

Cost per area —

Cost breakdown

Construction amount—

Site and foundation—

Finishes and fixtures—

Professional fees—

Permits and inspections—

Other expenses—

Contingency reserve—

Financing estimate

Estimated monthly payment —

Estimated total interest —

Cash needed —

Amount financed —

Affordability overview

Estimated housing/project payment—

Estimated debt-to-income ratio—

Target monthly debt limit—

Remaining monthly capacity—

Before using your estimate

Request written estimates from qualified contractors.
Confirm zoning, building permission, inspection, and utility requirements with the relevant local authority.
Check whether the existing structure can support the proposed addition.
Use a contingency reserve for unknown site conditions and design changes.
Review loan costs and repayment terms directly with your lender.