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Material, utility, and project planning calculators for home jobs.
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.
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.
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 home & construction 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 to size a project, compare materials, estimate a reserve, or decide whether a contractor quote is in the expected range.
Cross-check
Compare the estimate with local code, site measurements, supplier pricing, utility bills, permit rules, and contractor scopes before buying materials.
Watch for
Project estimates are sensitive to waste, labor, access, climate, soil, and existing conditions. Add contingency when the job cannot be measured cleanly.
This page belongs to the Home & Construction 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.
Measure the actual site
Square footage, slope, access, waste, existing conditions, and local material availability can change a project estimate quickly.
Add contingency
Cuts, breakage, delivery issues, weather, permits, and hidden repairs often make the real budget higher than a clean calculation.
Compare with local pricing
Supplier quotes, contractor scopes, code requirements, and permit fees should control the final budget.
Rerun this page after new measurements, contractor quotes, material price changes, permit comments, or scope changes.
Sources used for this calculator
These primary or official references help define the rules, terminology, safety checks, or source documents behind this estimate. Source links were checked in July 2026. They do not turn the calculator output into a quote, appraisal, tax determination, or professional opinion.
- Accessory Dwelling Units case study
HUD USER
Defines common attached, detached, and converted ADU forms; local zoning, building, utility, and permitting rules control feasibility and cost.
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.
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