ADU Cost Calculator

Detached ADU: Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.

ADU type

ADU sqft

Permit + impact fees

Utility hookups

Landscaping + site work

Total ADU cost

$208,000

Construction cost

$180,000

How the math works

600 sqft detached ADU at $300/sqft = $180K + $8K permits + $15K utilities + $5K landscaping = $208K all-in.

CA has streamlined ADU approvals (SB9, SB8). Many other states and cities have followed. Check local ADU program before starting design — can save $20K-$50K via pre-approved plans or fee waivers.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This ADU Cost Calculator is built to give a quick, browser-based estimate for adu cost. Detached ADU: Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.50-$450/sqft. Attached ADU: Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.50-$450/sqft. Attached ADU: Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.00-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.5K-$40K. This calculator sizes. ADU economics often depend heavily on local jurisdiction: California's SB9/SB8 laws have slashed permit timelines and fees for qualified projects. Pre-approved plan programs in many cities cut design cost 40-60%. Utility tap fees are the single largest wild card and should be researched with local agencies before committing to a budget — often Detached ADU: $150-$450/sqft. Attached ADU: $100-$300/sqft. Garage conversion ADU: $60-$200/sqft. Permits, utilities, landscaping adds $15K-$40K. This calculator sizes.0K-$25K of total cost lives here alone.5K-$40K. This calculator sizes.0K-$25K of total cost lives here alone. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the adu cost result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this adu cost estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Pick ADU type and sqft.
Add fees, utilities, landscaping.
See total cost.

Frequently Asked Questions

Which ADU type cheapest?

Garage conversion: lowest cost, fastest (2-4 months). Existing structure = less foundation/framing. Attached: mid. Detached new-build: most expensive but highest rental value and flexibility.

Permit and utility fees?

Permits $2K-$10K. Utility connections: $5K-$25K (sewer/water tap fees). Impact fees $2K-$15K in some CA cities. Add $15K-$50K total in fees before you buy lumber.

Financing?

ADU construction loan, HELOC, cash-out refi. Some states have ADU-specific programs (CA has CalHFA ADU Grant Program up to $40K). Start with the state and city resource office.