ADU Cost Calculator (2026) | Free USA Estimate

ADU Cost Calculator

Estimate adu cost in the United States. See low, average, and high costs, cost per sqft, material, labor, permits, timeline, FAQs, and related calculators.

Short answer

$139,823–$496,195

Average near $250,264 · about 16–40 weeks.

Material + labor Permit aware Local multiplier

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ADU Cost Calculator: what to expect

An accessory dwelling unit is essentially a small home, so it includes a kitchen, bath, and all systems — which is why per-square-foot cost rivals new construction. Garage conversions cost less than detached builds because the shell exists.

Across the United States, a adu cost averages $250,264 once mid-range materials, licensed labor, and standard permits are included. The figures below are a national baseline; pick your state or city to apply local labor rates, material delivery costs, and permit fees.

Cost summary

Low estimate	$139,823
Average estimate	$250,264
High estimate	$496,195
Cost per sqft	$233 - $827
Timeline	16-40 weeks

Where the money goes

For a typical adu cost, the average $250,264 estimate splits into roughly $99,797 of materials, $95,458 of labor, and $6,500 in permits.

Material cost	$99,797
Labor cost	$95,458
Permit cost	$6,500

What a adu cost includes

Foundation or converted shell
Full kitchen and bathroom
All systems: electrical, plumbing, HVAC
Insulation, drywall, and finishes
Permits, utility connections, and impact fees

What drives the cost the most

Detached new build vs. garage/basement conversion.
Full kitchen and bath plumbing and appliances.
Separate utility connections and impact fees.
Local ADU code and parking requirements.

Budget, standard, and high-end scopes

The $139,823–$496,195 range maps to three common levels of finish:

Scope	Roughly	What it covers
Conversion	$139,823	Garage or basement converted to a unit.
Attached ADU	$250,264	New space attached to the main home.
Detached ADU	$496,195	Standalone cottage with its own foundation.

How to save on a adu cost

Convert an existing garage or basement to skip foundation cost.
Check whether you can share utilities to avoid new connections.
Research local ADU incentives and pre-approved plan programs.

How this estimate is calculated

We start from a base cost-per-sqft for adu cost and adjust it for finish quality, labor complexity, waste, and equipment, then apply national baseline indices. The figures update with the cost data and reflect mid-range, licensed-contractor pricing, not a binding quote.

ADU Cost cost by city and state

The same adu cost costs more in high-wage metros and less in lower-cost markets. Below are typical 2026 ranges for major US cities, plus the highest- and lowest-cost states, all built from the national baseline of $139,823–$496,195 adjusted by local labor, material, and permit indices.

Cost in major US cities

City	Typical range	vs US avg
New York, NY	$216,236–$791,462	+55%
Los Angeles, CA	$205,311–$752,098	+47%
Chicago, IL	$156,482–$569,375	+12%
Houston, TX	$140,884–$500,667	+1%
Phoenix, AZ	$143,506–$510,370	+3%
Dallas, TX	$144,991–$515,442	+4%
Miami, FL	$159,959–$569,375	+15%
Atlanta, GA	$141,945–$505,139	+2%
Seattle, WA	$186,297–$672,738	+34%
Denver, CO	$165,682–$594,169	+19%
Boston, MA	$189,354–$682,994	+36%
Austin, TX	$155,992–$554,964	+12%

Highest- and lowest-cost states

State	Typical range	vs US avg
Hawaii	$204,610–$730,795	+48%
California	$198,396–$731,981	+42%
New York	$187,319–$683,231	+34%
Arkansas	$119,573–$425,748	−14%
West Virginia	$119,573–$425,748	−14%
Mississippi	$116,951–$416,045	−16%

We estimate adu cost costs across all 50 states and 30 metro areas. Compare costs by state or costs by city.

Questions homeowners ask first

How much does a adu cost cost in the United States?

In the United States, a adu cost typically runs $139,823 to $496,195, averaging $250,264. That assumes mid-range materials and a licensed contractor; budget finishes trend toward the low end and luxury scopes toward the high end.

What is the cost per sqft for a adu cost in the United States?

Expect roughly $233 to $827 per sqft in the United States. Multiply by your actual sqft count and add $6,500 in permits to size your own budget.

What drives the cost of a adu cost the most?

Detached new build vs. garage/basement conversion. Full kitchen and bath plumbing and appliances.

How long does a adu cost take in the United States?

Most adu cost projects run 16 to 40 weeks. Permit review, material lead times, and contractor scheduling are the usual reasons a timeline stretches.

How much of a adu cost is labor vs. materials?

On an average $250,264 adu cost in the United States, expect roughly $99,797 in materials and $95,458 in labor — labor is about 49% of the total. Labor share climbs in high-wage metros and on complex or structural work.

What is the difference between a budget and high-end adu cost?

A budget adu cost near $139,823 covers garage or basement converted to a unit. A high-end scope near $496,195 covers standalone cottage with its own foundation.

How can I save money on a adu cost?

Convert an existing garage or basement to skip foundation cost. Check whether you can share utilities to avoid new connections. Getting three local bids is the single biggest lever — pricing on the same adu cost scope can vary 20-30% between contractors.

Does a adu cost need a permit?

Most adu cost work that touches structure, plumbing, electrical, or egress needs a permit. We estimate $6,500 for the United States using local permit indices, but the building department sets the final fee.

Still comparing adu cost numbers?

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ADU Cost Calculator