500 sq ft ADU floor plans
500 sq ft fits a 1 bedroom ADU with a full bath, or a roomy studio. It's also the largest a junior ADU can be in California. Both layouts below are measured and open in the editor, where you can resize them and download a CAD file.
500 sq ft 1 bedroom
| Kitchen | 12'-10" x 8' |
|---|---|
| Bath | 6' x 8' |
| Laundry closet | 5' x 8' |
| Living | 14'-4" x 13' |
| Bedroom | 9'-6" x 13' |
$213K to $286K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
More floor plans to start from
500 sq ft studio
$213K to $286K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
450 sq ft junior ADU studio
$64K to $114K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
Studio or 1 bedroom at 500 sq ft
A studio keeps one open room plus the bath, which feels bigger and costs a little less. A 1 bedroom gives a door between sleeping and living, which renters and family members usually prefer.
At this size a compact, nearly square shape wastes the least space on hallways. Long and narrow works on tight side yards but needs about 475 sq ft or more.
California ADU size rules
- Detached ADU, largest
- Total floor area of a detached ADU can't exceed 1,200 sq ftGov. Code 66314(d)(5)
- What every city must allow
- A city can't use size, lot coverage or similar limits to block an ADU of at least 800 sq ft with 4 ft side and rear setbacksGov. Code 66321(b)(3)
- Attached ADU
- With an existing home, an attached ADU can't exceed 50 percent of the home's floor areaGov. Code 66314(d)(4)
- Junior ADU
- No more than 500 sq ft, inside the existing homeGov. Code 66333
Outside California, ADU size limits are set by each city or county. Your city's planning desk has the final word.
Will it fit your lot?
For homes in the California areas we cover, the free lot check reads your parcel, setbacks and local rules and shows the biggest unit that fits.
Check your lotQuestions
Can a 500 sq ft ADU have a bedroom?
Yes. A 500 sq ft 1 bedroom fits a bedroom of about 9.5 by 13 ft, a full bath, a laundry closet and an open kitchen and living room.
Is 500 sq ft a junior ADU?
Only if it's made inside the existing house. In California a junior ADU is at most 500 sq ft; a detached 500 sq ft unit is a regular ADU.
How much does a 500 sq ft ADU cost?
About $213K to $286K to build in Sacramento for these layouts. A junior ADU inside the house costs far less, about $64K to $114K at 450 sq ft. Add your ZIP in the editor for your area.
Last checked 2026-11-02. Costs are estimates priced at ZIP 95818, not bids. Floor plans are concept layouts; a licensed designer or architect prepares the plans your city approves.