Every national renovation calculator on the internet gives you the same useless number: "$150 per square foot for a home addition." That figure is the median of a dataset that includes rural Mississippi and downtown Manhattan, entry-level tract builds and custom millwork. It tells you nothing about what a 600-sqft addition costs in Arcadia in 2026. This calculator does.

Where the numbers come from

Two data sources. First, the City of Phoenix open-data permit export — every residential building permit pulled in the city in 2024–2025, with declared construction values, heated square footage, project type, and the address to cross-reference against Maricopa County property records [1]. Second, ExpandEase contractor calibration: we cross-referenced declared permit values against actual contractor invoices from 23 Phoenix-area renovation projects completed in 2025 [2]. The gap between what gets declared on a permit and what a project actually costs averaged 38% across our dataset. That gap is baked into every number in this calculator.

Room additions: $295–$420 per square foot

A standard livable room addition — one room with HVAC, electrical, and finishes that match the existing house — runs $295 to $420 per square foot all-in in Phoenix in 2026 [2]. The wide range is almost entirely explained by three variables: whether the foundation needs a new pour vs. a slab extension, how much structural modification the existing roofline requires, and finish level (builder-grade LVP flooring vs. hardwood vs. marble tile).

Room addition cost by size and quality — Phoenix 2026
SizeStandard (≈$250/sqft)Premium (≈$350/sqft)Luxury (≈$460/sqft)
200 sqft (small bedroom)$50K$70K$92K
400 sqft (bedroom + bath)$100K$140K$184K
500 sqft (suite or great room)$125K$175K$230K
700 sqft (large family room + bed)$175K$245K$322K
1,000 sqft (second floor half-story)$250K$350K$460K

All-in including GC overhead, pre-construction, and contingency. Excludes lot clearing and landscaping.

Master suite additions: $330–$465 per square foot

Master suite additions cost more per square foot than generic room additions because they require plumbing rough-in, tile work, and custom millwork (built-ins, closet systems) that inflate the cost per heated square foot. A 550-sqft master suite — bedroom, walk-in closet, primary bath — runs $181K to $256K at standard-to-luxury quality in Phoenix today [2]. The ARV impact is also stronger than a generic addition: master suite square footage appraises at roughly $580 per square foot in Arcadia, generating meaningful manufactured equity even at the high end of build cost.

ADU and guest house additions: $340–$490 per square foot

Detached ADUs are the most expensive addition type per square foot in Phoenix. The reason is the site work premium: every detached unit requires its own sewer lateral connection, a utility easement, and frequently an electrical service upgrade — costs that don't appear in per-sqft benchmarks and typically add $22K–$35K regardless of unit size [1]. A 600-sqft detached ADU in Phoenix runs $190K to $295K all-in, depending on quality. For the specific economics of ADUs in Phoenix — ARV impact, rental income model, and permit timelines — see our dedicated article on ADU cost in Phoenix [3].

Full gut remodels: $330–$510 per square foot

A full gut remodel — strip to studs, new MEP throughout, new finishes, new windows — runs $330 to $510 per square foot in Phoenix [2]. On a 1,500-sqft ranch, that's $495K to $765K all-in. The ARV impact is the highest of any project type: a fully renovated Arcadia ranch appraises at $690+ per square foot vs. $490–$520 for a comparable unrenovated property. On a 1,500-sqft footprint, that's a $255K–$300K ARV ceiling above the unrenovated value — partially or fully offsetting the renovation cost depending on scope and quality.

Kitchen remodels: $110K–$280K

A full gut kitchen remodel in Phoenix — new layout, new cabinets, new appliances, new countertops, new flooring — runs $110K to $280K depending on size and specification [2]. Per-square-foot benchmarks don't work well for kitchens because the cost is driven by cabinet linear footage, appliance tier, and countertop material, not heated floor area. A 200-sqft kitchen with $1,800/linear-foot custom cabinets, Sub-Zero/Wolf appliances, and quartzite counters runs $240K+. The same footprint with IKEA cabinets and standard appliances runs $110K. The ARV impact on a $900K Phoenix home is 8–12% depending on neighborhood, which is $72K–$108K — meaning premium kitchen renovations typically don't generate manufactured equity the way additions do, but they're table stakes for buyer appeal in Arcadia.

Primary bathroom remodels: $32K–$95K

Primary bathroom remodels in Phoenix range from $32K (builder-grade tile, standard fixtures, vanity update) to $95K+ (full layout reconfiguration, heated floors, custom tile work, steam shower) [2]. At $800–$1,200 per square foot, bathrooms are the most expensive room in the house by area — a reflection of the plumbing, waterproofing, and tile labor concentration in a 100–160 sqft space. ARV impact is 4–7% of home value on average — for a $900K Phoenix home, $36K–$63K — meaning a mid-spec bathroom remodel typically recovers 60–80% of cost in immediate ARV.

How to use this calculator

  • These are all-in Phoenix-market numbers, not contractor bids. Your actual cost will vary based on site conditions, existing structural issues, and current GC availability.
  • The "manufactured equity" output shows ARV gain minus project cost at the midpoint. It is not a guarantee — ARV projections depend on comp ceiling in your specific neighborhood.
  • Quality tier matters more than square footage for total cost. Moving from standard to luxury on a 500-sqft addition increases cost by ~$92K. Moving from 400 to 600 sqft at premium quality increases cost by ~$70K.
  • Financing changes the math. Most of these projects can be financed through an ARV-based renovation loan — you're borrowing against the completed value, not your current equity. Monthly payments on a $175K project at 7.5%, 30yr run ~$1,225/month.
  • Get a real estimate before committing. This calculator is the right starting point for the "is this plausible" question, not the final number before you sign a contract.