Home Addition Cost Calculator 2026: Room, Suite, 2nd Story
Home addition cost for 2026: Fixr puts a finished addition at $100–$300 per sq ft, typically $30,000–$100,000. Price yours by size, type and state.
Home Addition Cost Calculator
New floor area, outside length × width. A 12 × 15 ft bedroom is 180 sq ft.
Picks the lower, middle or upper third of the source's per-sq-ft range.
Adjusts the labor share by local construction wages (BLS, May 2025).
homeprojectestimator.com · · https://homeprojectestimator.com/calculators/home-addition-cost/
Estimated home addition cost
$66,350
Typical range $52,400 – $80,250
Cost per sq ft
$221.17
Where the money goes
- Single room (bedroom, office, family room): shell and finishes, installed $167–$233 per sq ft, materials and labor$50,000 – $70,000
- Architect or designer plans $2,000 – $8,400
- Building permits $400 – $1,850
National average. Pick your state and metro area to adjust the labor share (about 40% of this job) to local wages. Get three written quotes before you commit to a budget.
Per-sq-ft ranges from Fixr, HomeLight (citing HomeGuide and Angi) and Bob Vila; see Sources below. Site work on a steep or rocky lot, a new septic system, a panel upgrade and furniture are not included.
How to use this calculator
- Addition size. The new floor area in square feet. Measure the footprint from the outside of the new walls: a room that is 12 ft by 15 ft is 180 sq ft. For a second story, use the floor area of the new level, not the whole house.
- Type of addition. Each type has its own per-square-foot range from the sources below:
- Bump-out — pushes an existing wall out a few feet to enlarge a kitchen, bathroom or nook.
- Single room — a bedroom, office or family room on its own foundation.
- Primary suite — a bedroom with its own bathroom. The bathroom line is added automatically.
- Second story — a new level on top of the house.
- Sunroom — a glazed room; the low end is a three-season room, the high end a fully insulated four-season room.
- Finish level. Each source quotes one range per type. Basic uses the lower third of that range, mid-range the middle third, high-end the upper third. That split is this calculator's convention, not a figure from the sources.
- Includes a bathroom or kitchen. Each adds a line on top of the shell (see Cost breakdown).
- Architect or designer plans. On by default, since most permit offices want drawings for new floor area.
- Your state. Adjusts the labor share of the estimate to local construction wages.
Home addition cost in 2026
| Source | Typical range | Average | Per sq ft |
|---|---|---|---|
| Fixr (February 2025) | $30,000 – $100,000 | $65,000 | $100 – $300 |
| Bob Vila (May 2024) | $21,000 – $100,000 | $48,860 | $80 – $200 |
Sources: Fixr, House Addition Cost, updated February 3, 2025; Bob Vila, Building a Home Addition: Costs and Key Considerations, Explained, updated May 21, 2024.
Cost by size
| Addition size | Fixr range |
|---|---|
| 200 sq ft | $20,000 – $60,000 |
| 300 sq ft | $30,000 – $90,000 |
| 400 sq ft | $40,000 – $120,000 |
| 500 sq ft | $50,000 – $150,000 |
| 600 sq ft | $60,000 – $180,000 |
| 1,000 sq ft | $100,000 – $300,000 |
Source: Fixr, House Addition Cost, updated February 3, 2025.
Cost by type
| Type | Total | Per sq ft |
|---|---|---|
| Bump-out | $4,000 – $13,000 (Fixr) | $85 – $200 (HomeGuide, via HomeLight) |
| Bedroom | $30,000 – $100,000 (Fixr) | — |
| Primary bedroom suite | $37,500 – $117,000 (Angi, via HomeLight) | about $160 (Angi, via HomeLight) |
| Second story | $100,000 – $300,000 (Fixr) | $100 – $300, up to $500 for complex jobs (Bob Vila) |
| Sunroom | $35,000 – $70,000 (Fixr) | $100 – $350 (HomeGuide, via HomeLight) |
| Bathroom addition | $18,000 – $70,000 (Fixr) | $400 – $550 (Fixr) |
| Kitchen addition | $30,000 – $100,000 (Fixr) | — |
| Family room | $25,000 – $110,000 (Fixr) | — |
Sources: Fixr, House Addition Cost, February 3, 2025; Fixr, How Much Does It Cost to Add a Bathroom in 2026?, January 22, 2026; HomeLight, Adding a Bedroom or Office? How Much Does a Room Addition Cost?, June 4, 2026; Bob Vila, Building a Home Addition, May 21, 2024.
The calculator's per-square-foot bands: bump-out $85–$200, single room and primary suite $100–$300, second story $150–$300 (Bob Vila's 1,000 sq ft figure of $150,000–$200,000 sets the floor; Fixr's $300,000 example for 1,000 sq ft sets the top), sunroom $100–$350.
What drives the price
- Plumbing. Rooms with water cost the most per square foot. Fixr prices a stand-alone bathroom addition at $400–$550 per sq ft, against $100–$300 for a finished addition in general, and puts converting existing space to a bathroom at $200–$250 per sq ft.
- Foundation and roof. Every ground-floor addition needs both. Bob Vila prices foundation installation at $4,000–$12,000 and roof materials at $500–$5,000 per 100 sq ft. A small bump-out that cantilevers off the existing floor framing may avoid a new foundation; Bob Vila lists cantilevered additions separately at $15,000–$25,000.
- Going up instead of out. A second story skips the foundation and lot coverage limits but needs the existing walls and footings to carry the new load, the old roof removed, and a stair. Bob Vila puts it at $150,000–$200,000 for about 1,000 sq ft.
- Size. Fixed costs — design, permits, tying into the house — are spread over more square feet in a bigger addition, so cost per square foot falls as size rises even though the total climbs.
- Finishes. Fixr notes costs rise with elaborate finishes such as crown molding and decorative detail; flooring alone runs $3–$26 per sq ft on its component list.
- Design. Fixr puts design costs at 10%–17% of the final bill; Bob Vila gives $2,020–$8,400 for an architect.
Cost breakdown
- Shell and finishes, installed — square feet × the per-square-foot band for the type and finish level. The sources quote installed prices (materials and labor together), so the calculator does not invent a split between them. Fixr's component list shows what that covers: framing $15–$25 per sq ft, roofing $4–$30, insulation $0.65–$7.50, drywall $1.50–$3.50, electrical $3–$10, HVAC $2–$6, flooring $3–$26, painting $3–$4, windows $250–$1,500 each and doors $350–$2,200 each.
- Bathroom — $8,000–$25,000. This is Fixr's figure for building a bathroom inside an existing shell (a garage), because the addition's shell is already priced per square foot. Using Fixr's $400–$550 per sq ft for a stand-alone bathroom addition would count the walls and roof twice.
- Kitchen — $20,000–$40,000, Fixr's figure for a kitchen built inside an existing garage shell, for the same reason.
- Architect or designer plans — $2,020–$8,400 (Bob Vila).
- Building permits — $400–$1,850 (Bob Vila).
Not included: excavation on a difficult lot, a new septic system, an electrical service upgrade, landscaping repair (Bob Vila: $500–$2,500) and furniture. Bob Vila prices site prep and excavation at $1,276–$5,024 if your quote lists it separately.
Prices by state and metro area
Bob Vila puts labor at 30%–50% of an addition's price; the calculator uses 40%. That share is multiplied by the state's construction wage index — the state mean hourly wage for construction and extraction occupations divided by the national mean, from the U.S. Bureau of Labor Statistics' Occupational Employment and Wage Statistics, May 2025. Materials are left at the national price.
For the default 300 sq ft mid-range room with plans and permits ($66,350 nationally):
| State | Wage index | Typical estimate |
|---|---|---|
| Illinois | 1.25 | $73,000 |
| California | 1.20 | $71,650 |
| Texas | 0.84 | $62,100 |
| Mississippi | 0.78 | $60,500 |
For a closer number, choose your metro area as well as your state. At the default inputs the national estimate of $66,350 becomes $74,300 in Urban Honolulu, HI, where construction wages are 30% above the national mean, and $62,900 in Memphis, TN-MS-AR, 13% below it.
Addition, conversion or move?
Before you price new walls, price the space you already have. A garage or basement already has a foundation and a roof:
- The garage conversion cost calculator puts a 440 sq ft dry room at about $20,050, roughly $46 per sq ft.
- The basement finishing cost calculator prices the same kind of trade-off for a below-grade room.
An addition makes sense when neither exists, when the converted space would sit in the wrong place in the house, or when you need a bathroom and bedroom together on the main floor.
Permits, setbacks and engineering
Every addition adds floor area, so it needs a building permit, and most need separate electrical, mechanical and plumbing permits and inspections. Before you pay for drawings, ask your building department three questions: how close to the property line you can build (setbacks), how much of the lot can be covered, and whether a second story would exceed the height limit. Any one of these can rule out the addition you had in mind.
A second story or any addition that removes part of an exterior wall usually needs a structural engineer to confirm the existing framing, load-bearing walls and footings can take the new load. Treat the engineer's report as the first spend on a second story, not the last.
How to compare quotes and pay for it
Ask for quotes on the same drawings, split into foundation, framing, roofing, mechanical and finishes, with the permit and design fees shown separately. Large gaps between bids usually come from one quote excluding site work or assuming builder-grade finishes. Keep a contingency budget on top of the winning bid, and agree a draw schedule that pays for completed stages rather than paying far ahead.
Most additions are financed. The renovation loan payment calculator turns the estimate into a monthly payment for a home equity loan, HELOC or personal loan.
Sources
- Fixr, House Addition Cost — national average $65,000, typical $30,000–$100,000, $100–$300 per sq ft, cost by size and by type, component costs, design 10%–17% (updated February 3, 2025). link
- Bob Vila, Building a Home Addition: Costs and Key Considerations, Explained — $21,000–$100,000, average $48,860, $80–$200 per sq ft; second story; foundation, roof, permits $400–$1,850, architect $2,020–$8,400; labor 30%–50% (updated May 21, 2024). link
- HomeLight, Adding a Bedroom or Office? How Much Does a Room Addition Cost? — per-sq-ft rates for bump-outs and sunrooms (citing HomeGuide) and primary suites (citing Angi) (June 4, 2026). link
- Fixr, How Much Does It Cost to Add a Bathroom in 2026? — bathroom inside an existing shell $8,000–$25,000; stand-alone bathroom addition $400–$550 per sq ft (updated January 22, 2026). link
- Fixr, Cost to Remodel a Garage — kitchen inside an existing garage shell $20,000–$40,000 (updated January 31, 2025). link
- U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics, May 2025 — state construction wage index. link
Related
Frequently Asked Questions
How much does a home addition cost in 2026?
Fixr puts the national average at $65,000, with most additions between $30,000 and $100,000 and a finished addition at $100 to $300 per square foot (updated February 2025). Bob Vila's figures are lower: $21,000 to $100,000, an average of $48,860, and $80 to $200 per square foot. The type of addition and the finish level decide where you land.
How much does a 12x12 or 300 sq ft room addition cost?
Fixr prices a 200 sq ft addition at $20,000 to $60,000 and a 300 sq ft addition at $30,000 to $90,000. This calculator's 300 sq ft mid-range room with plans and permits comes to $52,400 to $80,250, typically about $66,350. Bob Vila prices a 10 x 12 ft bedroom (120 sq ft) at $9,600 to $24,000.
How much does a primary suite addition cost?
HomeLight, citing Angi, puts a primary bedroom suite at $37,500 to $117,000, or about $160 per square foot. The bathroom drives it: Fixr prices a bathroom built inside an existing shell at $8,000 to $25,000, and a stand-alone bathroom addition at $400 to $550 per square foot. A 400 sq ft mid-range suite in this calculator comes to about $102,850.
How much does it cost to add a second story?
Fixr gives $100,000 to $300,000; its high-end example is a 1,000 sq ft second-floor primary suite with a new roof at $300,000. Bob Vila quotes $150,000 to $200,000 for about 1,000 sq ft, $100 to $300 per square foot in general and up to $500 for complex jobs. The existing walls and foundation have to carry the new floor, which an engineer must confirm.
What is the cheapest kind of home addition?
A bump-out. Fixr prices one at $4,000 to $13,000 and Bob Vila at $4,000 to $9,000 on average, because it extends an existing room by a few feet instead of adding a new one. HomeLight, citing HomeGuide, gives $85 to $200 per square foot, so the low total comes from the small area, not a low rate.
How much does a sunroom addition cost?
Fixr puts a sunroom at $35,000 to $70,000 and Bob Vila at $25,000 to $80,000, with a prefabricated sunroom around $11,000. HomeLight, citing HomeGuide, gives $100 to $350 per square foot. A three-season room without heat sits at the low end; a four-season room that is heated and insulated like the rest of the house sits at the high end.
How much are permits and plans for an addition?
Bob Vila puts permits at $400 to $1,850 and an architect at $2,020 to $8,400. Fixr says design costs run 10% to 17% of the final cost. Almost every jurisdiction requires a permit for new floor area, and many require stamped drawings before they issue one, so both lines are in the calculator by default.