Calcscape

ADU Construction Cost Calculator

Scope a compact accessory dwelling unit with a clearer view of structural type, finished living space, wet rooms, and utility connection costs.

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Your project scope

ADU size (sq ft)
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ADU size (sq ft)

Enter the planned sq ft amount.

ADU type
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ADU type

New detached units carry a full foundation and exterior shell.

Finish tier
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Finish tier

Applies to flooring, cabinetry, finishes, and interior labor.

Kitchen & bath package
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Kitchen & bath package

Wet rooms are priced separately because fixtures and cabinets vary widely.

Utility hookups
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Utility hookups

Distance and capacity at the main home strongly affect hookup work.

Your state
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Your state

Scales U.S.-average labor and material midpoints for typical state-level pricing. It is not an on-site bid.

How to use this calculator

  1. Enter the adu size (sq ft).
  2. Choose each scope driver to reflect your project.
  3. Select your state for cost scaling.
  4. Review the itemized components before requesting bids.

Results explained

This model uses separate construction components rather than a single blanket rate. The band reflects common variation in access, design, and contractor pricing.

Quick reference: ADU Construction Cost cost drivers

Installed U.S.-average midpoints before the selected state adjustment.

ScopeMidpoint
Detached standard ADU$250/sq ft
Garage conversion structure$155/sq ft
Full kitchen & bath$42,000
Major utility work$30,000

These are planning midpoints, not a site inspection, engineering opinion, or contractor proposal.

How the estimate is built

The structural type is the main per-square-foot line, with finish, wet-room, utility, and permit allowances displayed separately.

Example scenario

A 650 sq ft detached, mid-finish ADU with a full package and nearby tie-in starts near $250,000 at U.S. average.

FAQ

Can I build an ADU on my lot?

Rules vary by city, HOA, lot coverage, and utility capacity.

Are design fees included?

The permit line is a planning allowance, not a full architect or engineering agreement.

Does this include rental furnishings?

No. This is construction scope only.