500 sq ft ADU Cost (2026)
A 500 sq ft ADU is the most popular size for a 1-bedroom rental and the largest footprint that qualifies for impact fee waivers in many states. Here is what it costs to build in 2026, what it rents for, and how to finance it.
Last updated: •Reviewed by the aduglossary editorial team
Quick Facts: 500 sq ft ADU
National cost range
$140K–$320K
Detached new-build, all-in
Cost per sq ft
$280–$640/sf
Higher per-sf than 700–800 sf builds
Typical layout
1BR / 1BA + kitchen
Or large studio + full bath
Build timeline
5–9 months
Faster than 800–1,200 sf builds
Rental income
$1,200–$2,500/mo
Depending on metro
Impact fee status
Waived in CA (under 750 sf)
Reduced in many other states
500 sq ft ADU Cost by Metro
All-in costs for a 500 sq ft detached new-build ADU at a standard finish level. Sorted from highest-cost to lowest-cost market.
| Metro | Detached new-build | Garage conversion | Per-sf range |
|---|---|---|---|
| San Jose / SF Bay Area | $250K–$320K | $140K–$200K | $500–$640 |
| Seattle | $240K–$300K | $130K–$190K | $480–$600 |
| Los Angeles | $200K–$280K | $120K–$180K | $400–$560 |
| San Diego | $190K–$260K | $115K–$170K | $380–$520 |
| Denver | $200K–$270K | $120K–$175K | $400–$540 |
| Portland | $180K–$240K | $110K–$160K | $360–$480 |
| Sacramento | $160K–$220K | $95K–$145K | $320–$440 |
| Phoenix / Scottsdale | $150K–$210K | $90K–$140K | $300–$420 |
| Austin / Houston / Dallas | $140K–$200K | $80K–$130K | $280–$400 |
Want a city deep dive? See Sacramento, Denver, Houston, Los Angeles, San Diego, or San Jose.
Why 500 sq ft Is the Sweet Spot
500 square feet sits at a useful intersection of zoning, financing, and rental demand. It is large enough for a real 1-bedroom unit but small enough to qualify for the most generous regulatory treatment in many states:
- • Impact fee waivers — California waives impact fees on all ADUs under 750 sq ft. Many other states cap fees on sub-500 sq ft units.
- • JADU eligibility (CA) — 500 sq ft is the upper limit for a Junior ADU, which can be permitted as a fast-track conversion of existing space within the primary residence.
- • Setback flexibility — many cities offer reduced setbacks for ADUs under 800 sq ft, allowing you to fit a unit on smaller lots.
- • Rental demand — the 1BR / studio rental segment has the lowest vacancy in most major metros. A 500 sq ft unit competes directly with new-construction studios at far lower build cost.
- • Financing simplicity — $150K–$250K builds fit comfortably inside HELOC and renovation loan caps, avoiding the more complex construction-perm structure.
The trade-off is the per-square-foot premium. Going from 500 to 700 sq ft typically adds only $40K–$70K to the total but lowers the per-sf number by 15–25%. If your zoning and budget allow, sizing up usually pays back through higher rent.
Typical 500 sq ft Floor Plan
A well-laid-out 500 sq ft ADU comfortably fits a separate 1-bedroom configuration. Here is the rough allocation most architects recommend:
- • Bedroom: ~120 sq ft — fits queen bed and small dresser
- • Bathroom: ~50–65 sq ft — full bath with shower (skip the tub)
- • Kitchen: ~80–100 sq ft — galley layout with full-size appliances
- • Living / dining: ~180–220 sq ft — combined
- • Storage / closet / mechanical: ~30–50 sq ft
For pre-approved 500 sq ft plans, check California's AB 1332 program.
Get a Personalized 500 sq ft Estimate
The free calculator factors in your city, finish level, and ADU type to give you a tighter range than the table above.
Run the ADU Cost Calculator →Finance Your 500 sq ft ADU
$140K–$320K builds typically fit a HELOC or renovation loan. See the financing options guide or run scenarios in the loan calculator.
Frequently Asked Questions
How much does a 500 sq ft ADU cost in 2026?
$140K-$320K all-in nationally for a 500 sq ft detached new-build ADU. The Bay Area and Seattle run $250K-$320K; LA and San Diego $190K-$280K; Denver, Sacramento, and Portland $160K-$240K; Houston, Phoenix, and Dallas $140K-$210K. Garage conversions of similar footprint run 30-40% lower.
Why is a 500 sq ft ADU often more expensive per sq ft than a 700 sq ft ADU?
Permits, utility hookups, design fees, and site mobilization are roughly fixed regardless of size. Spreading those costs over 700 sq ft instead of 500 sq ft lowers the effective per-sf rate. A 500 sq ft ADU often runs $380-$500/sf, while a 700 sq ft on the same lot can land at $320-$420/sf.
Is 500 sq ft enough for a 1-bedroom ADU?
Yes. 500 sq ft is the sweet spot for a comfortable 1-bedroom plus bath plus kitchenette. Most 500 sq ft ADUs include a separate bedroom, full bathroom, full kitchen, and a combined living/dining area. This is also the size most California cities allow as a JADU under streamlined rules.
Are 500 sq ft ADUs exempt from impact fees?
Yes in California - state law (Gov. Code 65852.2) waives impact fees on ADUs under 750 sq ft. Most other states do not have a comparable exemption, but many cities offer reduced fees for sub-750 sq ft units. Check your local fee schedule.
What rental income can I expect from a 500 sq ft ADU?
$1,200-$2,500/month nationally. The Bay Area, Seattle, and LA hit the top of the range; Sun Belt metros run $1,200-$1,700. Studio and 1BR ADUs at 500 sq ft tend to rent within 2 weeks in tight metros.
Can I finance a 500 sq ft ADU build?
Yes. HELOC is most common when you have $100K+ equity. RenoFi and construction-perm loans cover the full build amount on a single loan. DSCR loans qualify based on projected rent if you plan to rent the ADU out. Use the loan calculator to compare monthly payments.
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