US calculator
Home Addition Cost Calculator
Estimate the cost of adding a specific type and amount of new living space to a US home.
How this estimate is calculated
Added floor area uses a US living-space construction baseline. Addition type and story materially change per-square-foot cost, while finish applies a calibrated percentage. Engineering, major electrical work, and HVAC extension remain fixed allowances.
This is a planning estimate, not a contractor quote. Actual contractor quotes vary by location, specification, site conditions, labour, and project requirements.
Useful cost information
Planning assumptions
- This estimates a specific new living-space addition rather than a generic whole-project extension profile.
- Permits, architecture, site preparation, demolition, utility relocation, and unusual foundations may be separate.
- Standard construction is already represented and is not added again.
Data sources & methodology
Angi — current home-addition cost guidance
Last reviewed: 2026-09
Helpful guides
Concrete Slab Cost Guide: Size, Thickness, Reinforcement and Labor
Slab area is only the start: thickness, support, reinforcement, access, finishing, and site work shape the installed project.
Garage Building Cost Guide: Attached, Detached and Size-Based Costs
A garage build combines structure, envelope, doors, utilities, site access, and approvals—not just floor area and a car-count label.
Attached vs Detached Garage Cost: Which Is Better for Your Project?
Attached and detached garages shift costs between house integration, independent construction, utilities, access, and site work.
Home Addition Cost Guide: Cost per Square Foot, Rooms and Project Scope
Equal-size additions can have very different costs when rooms, services, structural work, site conditions, and tie-ins change.
Build Up vs Build Out: Second-Story and Ground-Floor Addition Cost Comparison
Building up and building out move cost between existing-structure integration, new foundations, roof work, circulation, site use, and disruption.
House Rewiring Cost Guide: Labor, Materials and Electrical Panel Work
A rewiring budget must cover more than cable: circuit scope, access, testing, control equipment, wall repairs, and disruption can reshape the project.
Does Your House Need Rewiring? Warning Signs, Scope and Replacement Costs
Electrical observations can justify prompt evaluation, but they do not remotely diagnose the cause or prove a whole-house rewire is required.
Whole-House Plumbing Replacement Cost Guide: Pipes, Labor and Access
Repiping cost follows pipe routes and access as much as floor area: fixture density, material, openings, reconnections, and making-good define the real project.