Free tools
Orange County, CaliforniaFree ADU calculators.
Run the numbers before you talk to anyone.
Every Avorino tool in one place: price a build, model the rent, size the loan, check your city’s permit reality.
In this set
Not sure which ADU calculator you need?
The cost calculator answers what a build costs, the ROI calculator what it earns back, the loan calculator what the monthly payment looks like, and the garage conversion calculator prices a conversion rather than a new build.
- ADU Cost Calculator
- ADU ROI Calculator
- Garage Conversion Cost Calculator
- ADU Loan Calculator
The toolbox (7)
Seven ways to find your number.
Four calculators that price a build, model the rent and size the loan, a property check that reads your own parcel, and two references that tell you what your city will actually ask for.
01 ADU Cost Calculator
Get an instant, detailed cost breakdown based on your property location, ADU size, and finish level. Powered by real Orange County market data.
Run your numbers- Calculator
- $85K – $440K+
- All ADU types · typical OC range
02 ADU ROI Calculator
See your projected rental income, property value increase, and payback timeline. Make confident investment decisions with real numbers.
See your return- Calculator
- 6.4 yrs
- Payback · 800 sqft detached · Irvine
03 Garage Conversion Cost Calculator
Price a garage conversion on your own garage: square footage, finish level, and what the permit and utility work really adds.
Price your garage- Calculator
- $85K – $170K+
- Permitted conversion
04 ADU Loan Calculator
Work out the monthly payment, total interest, and what an ADU build costs to finance across the terms lenders actually offer.
Size your payment- Calculator
- 4 routes
- HELOC · cash-out · construction · renovation
05 ADU Eligibility Check
Enter an Orange County address and see what state ADU law allows on that parcel: lot size, terrain, hazard overlays, sewer or septic, HOA and overlay zoning, each field with its source.
Check your lot- Property check
- 800 sq ft
- State floor · detached ADU, every OC city
06 OC ADU Permit Index
Permit reality for every Orange County city and community: who reviews, what they ask for, and the local quirks that set the calendar.
Look up your city- Reference
- 37
- OC cities & communities covered
07 ADU Plan Samples
Real floor plans we build from, with square footage and layout, and a per-plan price on request.
Browse the plans- Reference
- 387 – 830 sq ft
- Plans we build from
How owners use these
From your lot to a real bid.
The lot first, then the city, the build, the return and the loan. When the number looks right, put a real bid behind it.
01 / 06
Check what your lot allows
Enter an Orange County address and see what state ADU law allows on that parcel: lot size, terrain, hazard overlays, sewer or septic, HOA and overlay zoning, each field with its source.
ADU Eligibility Check · 800 sq ft
02 / 06
Look up your city's permit reality
Permit reality for every Orange County city and community: who reviews, what they ask for, and the local quirks that set the calendar.
OC ADU Permit Index · 37
03 / 06
Price the build
Get an instant, detailed cost breakdown based on your property location, ADU size, and finish level. Powered by real Orange County market data.
ADU Cost Calculator · $85K – $440K+
04 / 06
Model the rent
See your projected rental income, property value increase, and payback timeline. Make confident investment decisions with real numbers.
ADU ROI Calculator · 6.4 yrs
05 / 06
Size the loan
Work out the monthly payment, total interest, and what an ADU build costs to finance across the terms lenders actually offer.
ADU Loan Calculator · 4 routes
06 / 06
Put a real bid behind the estimate.
The calculators price the build; we build it. Tell us what you're planning and we'll turn your numbers into a scoped, licensed bid.
Built by Avorino · Brea
Step into the kitchen.
The finished kitchen of the Brea conversion, in one slow move.
- 01 / 03The kitchenWhite shaker cabinets over a marble-look backsplash.
- 02 / 03StainlessA gas range, a dishwasher and a stainless refrigerator.
- 03 / 03To the yardA glass slider opens the kitchen to the yard.
Where the numbers come from
Priced against builds like these.
The calculators are calibrated on finished Avorino projects across Orange County. Tap any project for the full set.
01 / 08
Questions
Quick answers
What does your ADU loan calculator show?
We work out the monthly payment, total interest, and what an ADU build costs to finance across the terms lenders actually offer.
What information does your ADU cost calculator use?
We use your property location, ADU size, and finish level for a detailed cost breakdown. Our ADU Cost Calculator is powered by real Orange County market data.
Can your ADU calculator show projected rental income?
We show your projected rental income, property value increase, and payback timeline with our ADU ROI Calculator.
Can I calculate garage conversion costs for my own garage?
We price a garage conversion on your own garage: square footage, finish level, and what the permit and utility work really adds.
Can I check what ADU law allows on my Orange County property?
We show what state ADU law allows on your parcel when you enter an Orange County address. Our ADU Eligibility Check covers lot size, terrain, hazard overlays, sewer or septic, and overlay zoning, each field with its source.
When the number looks right
Put a real bid behind the estimate.
The calculators price the build; we build it. Tell us what you're planning and we'll turn your numbers into a scoped, licensed bid.
Free estimate
Your project, in three quick steps.
- 01Project
- 02Plans
- 03Context
- 04Contact
Service areas
Serving 37 Orange County cities & communities, plus unincorporated OC and nearby LA County.
- Aliso Viejo ADU tools
- Anaheim ADU tools
- Brea ADU tools
- Buena Park ADU tools
- Corona del Mar ADU tools
- Costa Mesa ADU tools
- Coto de Caza ADU tools
- Cypress ADU tools
- Dana Point ADU tools
- Fountain Valley ADU tools
- Fullerton ADU tools
- Garden Grove ADU tools
- Huntington Beach ADU tools
- Irvine ADU tools
- La Habra ADU tools
- La Palma ADU tools
- Ladera Ranch ADU tools
- Laguna Beach ADU tools
- Laguna Hills ADU tools
- Laguna Niguel ADU tools
- Lake Forest ADU tools
- Las Flores ADU tools
- Los Alamitos ADU tools
- Mission Viejo ADU tools
- Newport Beach ADU tools
- Orange ADU tools
- Placentia ADU tools
- Rancho Santa Margarita ADU tools
- Rossmoor ADU tools
- San Clemente ADU tools
- San Juan Capistrano ADU tools
- Santa Ana ADU tools
- Stanton ADU tools
- Tustin ADU tools
- Villa Park ADU tools
- Westminster ADU tools
- Yorba Linda ADU tools
- Unincorporated Orange County ADU tools
- Unincorporated LA County ADU tools