ADU / In-Law Suite

What Will Your ADU Cost and Earn?

Estimate the cost to build an accessory dwelling unit, plus monthly rental income and payback period, adjusted for your region. Free and instant.

Estimate my ADU
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ADU type Step 1 of 4

What Type of ADU?

Each type has a different cost and permit profile.

Estimates include build, permits and chosen features. Rental income is indicative and varies by local market. Confirm with contractor bids and local rules.

How the ADU Calculator Works

Type, size and finish drive the build cost; size and region drive the rental estimate.

1. Pick the Type

Attached, detached, garage or basement conversion, each with its own rate and permit cost.

2. Size, Finish, Layout

Set square footage and finish, then add layout and utility features your unit needs.

3. See Cost and Income

Get a build-cost range plus estimated monthly rent and how long it takes to pay back.

Typical Cost per Square Foot by ADU Type

National averages from economy to premium finishes, before permits ($5k to $12k) and layout features. Your estimate is then adjusted for your state’s construction costs.

Detached ADU $276 to $520 / sq ft
Attached ADU $234 to $440 / sq ft
Basement Conversion $191 to $360 / sq ft
Garage Conversion $170 to $320 / sq ft

ADUs as an Income Investment

The rent an ADU earns can offset much of its build cost over time.

Monthly Rental Income

A finished ADU can rent for one to three dollars per square foot per month depending on your market.

Payback Period

Dividing build cost by annual rent shows how many years the unit takes to pay for itself.

Added Home Value

Beyond rent, an ADU adds living space and resale appeal that appraisers and buyers reward.

Local Rules Matter

ADU rules, owner-occupancy and parking requirements vary by city. Check local zoning before you commit.

ADU Cost FAQ

How much does it cost to build an ADU?
Most accessory dwelling units run from about $170 to $520 per square foot depending on type, finish and region, before permits and utilities. A detached ADU costs the most per square foot; a garage conversion the least.
Can I rent out an ADU?
In most areas yes, and rental income is the main reason owners build them. This calculator estimates monthly rent and a payback period based on your size and region.
Which ADU type is cheapest?
Converting an existing garage or basement is usually cheapest because the shell already exists. Detached new-build ADUs cost the most because they need a new foundation, roof and separate utilities.
Do ADUs add value to my home?
Yes. ADUs add usable square footage and rental potential, both of which buyers and appraisers value. The income can also offset much of the build cost over time.
Is the calculator free?
Yes. It is free and gives an instant cost range, rental estimate and payback period plus an emailed copy.

Estimate Your ADU Now

Get build cost, rental income and payback, then connect with vetted local contractors for real quotes.

Start the calculator