Statistics

ADU size statistics

44 of 54 figures are HyreADU calculations. Permitted floor area on 8,536 new-construction Los Angeles ADU permits, against the five square-foot numbers written into California statute.

Updated September 2026 · Data as of LADBS Socrata resource pi9x-tg5x (409,619 rows) analyzed 2026-09-05, departmental refresh to 2026-08-30; Government Code §§ 66311.5, 66313, 66314 and 66321 retrieved 2026-09-05; Census Manufactured Housing Survey annual tables retrieved 2026-09-07

Written by HyreADU Research Desk Primary-source research and data analysis

Audited by HyreADU Research Desk Provenance and citation audit

920 sq ft median permitted floor area, new-construction ADU, City of Los Angeles HyreADU calculation over 8,536 permits, 2020–2026. Interquartile range 670–1,194 sq ft.

7% as many permits immediately above the 1,200 sq ft cap as immediately below it HyreADU calculation: 79 permits in the 1,200–1,250 bin against 1,066 in the 1,150–1,200 bin. The cliff is the statute, not the market.

44 of 54 figures are HyreADU calculations 44 HyreADU calculation · 8 Agency published · 2 Trade / survey estimate. Below one-third we publish the study instead of a digest.

How to use this page

Almost every published “average ADU size” is a builder’s rule of thumb with no file behind it. This page is the measured distribution.

Across 8,536 City of Los Angeles building permits for new construction adding an accessory dwelling unit, issued 2020–2026, the median recorded floor area is 920 sq ft, the mean is 975 sq ft, and the interquartile range runs 670 to 1,194 square feet.

The distribution is not shaped like a distribution of household needs. It has two modes sitting immediately below two numbers in the Government Code. The tallest bin in the whole file is 1,150–1,200 square feet with 1,066 permits — and the very next bin holds 79, 7% of it.

635 permits are recorded at exactly 1,200 square feet, the detached cap in Government Code § 66314(a)(5).

The second mode sits at 750–800 square feet (673 permits), on the 800-square-foot constructability floor in § 66321 and just above the 750-square-foot impact-fee threshold in § 66311.5.

Type changes the answer more than taste does. Median floor area is 920 sq ft for new construction, 480 sq ft for a garage conversion, and 409 sq ft for a junior ADU — 76% of junior permits sit at or below the 500-square-foot statutory maximum.

44 of 54 figures on this page are HyreADU calculations (44 hyreadu calculation, 8 agency published, 2 trade / survey estimate). Every calculation links to the size-distribution study.

This is a Los Angeles measurement. There is no California ADU size distribution here, and no national one, because no agency publishes a file that would support either.

Read the provenance, not just the number

A statistic about ADU size is only as good as the file it was measured on, and most published ones have no file at all. Every figure below is one of three things, and it says which on the row.

HyreADU calculation — we downloaded the City of Los Angeles permit extract, built the frame, and computed the percentile, share or ratio ourselves.

The frame rules and the caveats live on the size-distribution study.
Agency published — a statutory threshold quoted from the Government Code, or a Census table.

We cite the section and the table, never an article about them.
Trade / survey estimate — Chapple, Ganetsos and Lopez’s 2021 owner survey for bedroom mix. A survey of a 2018–19 cohort, labeled as what it is.

What the floor-area field is. square_footage is the department’s field on the permit record. It is not a HyreADU measurement of a finished building, and on alteration permits it can describe the scope of work rather than the completed unit.

That is exactly why the headline frame here is new construction only — 8,536 permits with a usable value out of 9,374 in the new-construction frame, with 838 dropped as out of range.

What it is not. A permit is an intention, not a building. A recorded 1,200 is a number a plan checker accepted, not a tape measure across a finished floor. And the whole file is one city.

Los Angeles is the only California jurisdiction this desk has found publishing a departmental ADU flag on a complete permit extract, which is why the geography column on every own-calculation row says City of Los Angeles and nothing broader.

The figures most worth knowing

920 sq ft Median floor area, new-construction ADU permit HyreADU calculation · 8,536 permits

635 permits recorded at exactly 1,200 sq ft — the detached cap HyreADU calculation · § 66314(a)(5)

26.0% of new-construction permits sit in the 1,100–1,200 sq ft band HyreADU calculation · one 100 sq ft band

32.5% sit at or below 750 sq ft, the impact-fee threshold HyreADU calculation · § 66311.5

409 sq ft median floor area on a junior ADU permit HyreADU calculation · statutory maximum 500 sq ft

Full method, frame rules and limitations on the size-distribution study.

The distribution, and the two numbers it is piled against

Below is the shape of 8,536 new-construction ADU permits in 50-square-foot bins.

Two features are worth more than the median: the mode at 1,150–1,200 square feet, immediately below the detached cap, and the mode at 750–800, on the constructability floor.

Neither is where a family would land by preference. Both are where a rule stops.

The tallest bar in the file is the last one before the cap. Above 1,200 square feet the distribution falls to 7% of its modal height and never recovers — those 12.5% of permits are attached units, whose ceiling under § 66314(a)(4) is 50 per cent of the primary dwelling rather than a flat number, plus records the department coded differently. Chart: HyreADU Research Desk, from the same bin counts tabulated below. LADBS resource pi9x-tg5x, analyzed 2026-09-05.

Band	Permits	Share of the file	Why this band	Class
Up to 500 sq ft	1,211	14.2%	The junior-ADU maximum in § 66313. Studios and small back-lot units.	HyreADU calculation
501–750 sq ft	1,566	18.3%	Still inside the § 66311.5 impact-fee exemption at 750 sq ft.	HyreADU calculation
750–800 sq ft	673	10.4%	The § 66321 constructability floor. 254 permits sit at exactly 800; 35 at exactly 750.	HyreADU calculation
800–1,100 sq ft	1,579	18.5%	The genuinely unconstrained middle. No statutory number sits here.	HyreADU calculation
1,100–1,200 sq ft	2,220	26.0%	The largest concentration in the file. 1,061 permits fall in the last five square feet alone.	HyreADU calculation
Above 1,200 sq ft	1,068	12.5%	Above the detached cap: attached units on a proportional ceiling, plus coding differences.	HyreADU calculation

Band counts are the share multiplied by 8,536 and rounded, so they will not sum exactly. The underlying bin counts are exact and are the bars in the chart. Every row is a HyreADU calculation over the LADBS extract.

The 800-square-foot number is not a permission to build 800 square feet. § 66321 says a local agency’s development standards may not defeat an 800-square-foot unit with four-foot side and rear setbacks. Builders read that as a floor and design to it, which is why the bin exists.

The five statutory numbers, and how many permits sit on each

California ADU law contains five square-foot numbers. Two are ceilings, one is a floor, one is a fee line, one is a definition. Read together they explain the shape of the distribution better than any account of household preference does.

Square feet	What the statute does with it	Section	Measured in the LA file	Class
500	Defines a junior accessory dwelling unit: “no more than 500 square feet of interior livable space … contained entirely within a single-family residence”.	§ 66313	76.0% of 2,238 junior permits sit at or below it; 14.2% of new-construction permits do.	Agency published + HyreADU calculation
750	No impact fee may be imposed on an ADU of 750 sq ft or less. Above it, impact fees are charged proportionately to the primary dwelling.	§ 66311.5	32.5% of new-construction permits are at or below it. 35 are recorded at exactly 750.	Agency published + HyreADU calculation
800	A local development standard may not prevent an 800 sq ft unit with four-foot side and rear setbacks from being built.	§ 66321	254 permits at exactly 800; the 750–800 band holds 10.4% of the file.	Agency published + HyreADU calculation
1,200	The total floor area of a detached ADU shall not exceed 1,200 square feet.	§ 66314(a)(5)	635 permits at exactly 1,200; 1,061 in the final five square feet; only 12.5% above.	Agency published + HyreADU calculation
50% of the primary	The ceiling for an attached ADU is proportional, not a flat number.	§ 66314(a)(4)	Why a minority of permits legitimately exceed 1,200 sq ft. The file does not distinguish attached from detached, so we do not claim it does.	Agency published

Statutory text retrieved from leginfo.legislature.ca.gov on 2026-09-05. The section numbers matter. These provisions were recodified twice in under two years — AB 2221 and the 2024 renumbering moved the old § 65852.2 material into the 66310-series, and SB 543 (Stats. 2025, Ch. 520) then moved § 66324 to § 66311.5, § 66327 to § 66313.5 and § 66332 to § 66311.7 with effect from 1 January 2026.

Any page still citing § 65852.2 is quoting a repealed section number.

Use the size envelope calculator to work your own lot against these numbers. It applies the statute; it does not promise your city will agree.

Size by ADU type: three different products

A single “average ADU size” hides the fact that the three common routes produce units of visibly different size. The conversion is small because it inherits a garage footprint. The junior unit is small because the statute caps it. Only new construction is sized by choice — within the cap.

New construction, median920 sq ft

8,536 permits

Garage conversion, median480 sq ft

17,937 permits · see the garage-conversion digest

Junior ADU, median409 sq ft

2,238 permits · 500 sq ft statutory maximum

Type	n	p10	p25	Median	p75	p90	Class
New construction (detached and attached)	8,536	460 sq ft	670 sq ft	920 sq ft	1,194 sq ft	1,343 sq ft	HyreADU calculation
Garage conversion	17,937	329 sq ft	373 sq ft	480 sq ft	745 sq ft	1,193 sq ft	HyreADU calculation
Junior ADU	2,238	265 sq ft	353 sq ft	409 sq ft	499 sq ft	1,378 sq ft	HyreADU calculation

A new-construction ADU is 1.92× the median garage conversion and 2.25× the median junior unit.

The junior distribution has a long right tail — p90 is 1,378 sq ft, above the 500 sq ft statutory maximum — because the junior flag and the ADU flag can both be set on one permit and the recorded area then describes the whole scope. We publish the tail rather than trim it.

The garage-conversion numbers are the subject of their own digest at /statistics/garage-conversion/; junior units are covered in the junior ADU study.

One statute, seven medians

Everything in the previous tables is city-wide. Split the same file by area planning commission and the median moves 377 square feet — inside a single jurisdiction, under one set of state size rules. Lot size, not law, is doing that work.

The Valley builds large: North Valley’s median is 1,104 sq ft, and 37.3% of its permits land in the single 1,100–1,200 band. West Los Angeles builds small: median 727 sq ft, with 53.5% at or below 750 square feet. Chart: HyreADU Research Desk, from the same percentiles tabulated below. LADBS resource pi9x-tg5x, analyzed 2026-09-05.

Area planning commission	n	p25	Median	p75	≤750 sq ft	1,100–1,200 sq ft	Class
North Valley	2,422	799 sq ft	1,104 sq ft	1,200 sq ft	19.9%	37.3%	HyreADU calculation
South Valley	2,456	727 sq ft	953 sq ft	1,196 sq ft	28.5%	28.9%	HyreADU calculation
South Los Angeles	1,355	622 sq ft	878 sq ft	1,163 sq ft	37.3%	18.3%	HyreADU calculation
Harbor	243	701 sq ft	858 sq ft	1,189 sq ft	32.1%	18.1%	HyreADU calculation
Central	400	532 sq ft	798 sq ft	1,178 sq ft	45.3%	17.0%	HyreADU calculation
East Los Angeles	801	559 sq ft	784 sq ft	1,143 sq ft	46.1%	19.5%	HyreADU calculation
West Los Angeles	859	480 sq ft	727 sq ft	1,020 sq ft	53.5%	10.6%	HyreADU calculation

All seven rows are HyreADU calculations over the same extract. The city-wide median of 920 sq ft is real, and it describes none of these seven areas well. A statewide “average ADU size” would hide a spread larger than this one.

Where the units are being built, rather than how big they are, is the subject of the geography study.

Has the typical ADU got bigger?

The median has barely moved. The top of the distribution has moved a great deal. That combination — a flat middle and a rising tail — is the signature of a small number of large units entering a file whose center is pinned by statute.

Year of issue	n	p25	Median	p75	p90	Mean	Class
2020	580	600 sq ft	938 sq ft	1,182 sq ft	1,200 sq ft	892 sq ft	HyreADU calculation
2021	963	634 sq ft	950 sq ft	1,190 sq ft	1,200 sq ft	923 sq ft	HyreADU calculation
2022	1,572	631 sq ft	892 sq ft	1,189 sq ft	1,200 sq ft	939 sq ft	HyreADU calculation
2023	1,384	695 sq ft	944 sq ft	1,198 sq ft	1,304 sq ft	997 sq ft	HyreADU calculation
2024	1,401	685 sq ft	912 sq ft	1,191 sq ft	1,462 sq ft	992 sq ft	HyreADU calculation
2025	1,598	705 sq ft	922 sq ft	1,197 sq ft	1,600 sq ft	1,007 sq ft	HyreADU calculation
2026	1,038	665 sq ft	872 sq ft	1,199 sq ft	1,817 sq ft	1,024 sq ft	HyreADU calculation

Median floor area moved -66 square feet between 2020 and 2026 while the 90th percentile moved +617.

The p75 sits within a few square feet of 1,200 in every single year of the window — the cap is the most stable feature of the whole series. 2026 is a partial year: the department’s own refresh field runs to 2026-08-30.

Permit valuation over the same window is on the valuation study, and it moved far more than floor area did.

Why the factory product does not fit the statute

A reader comparing a site-built ADU with a HUD-Code manufactured home is comparing two product lines that are sized for different purposes. The Census publishes floor area for the second one, and the comparison is unflattering to the idea that you can simply buy a manufactured home and call it an ADU.

Product	Average floor area	Median floor area	Against the 1,200 sq ft detached cap	Class
New HUD-Code manufactured homes, all sizes, Census West region, 2025	1,369 sq ft	1,325 sq ft	169 sq ft above it on average	Agency published + HyreADU calculation
Single-section only, Census West region, 2025	944 sq ft	916 sq ft	Comfortably inside it	Agency published
Double-section only, Census West region, 2025	1,532 sq ft	1,511 sq ft	Above it	Agency published
New-construction ADU permits, City of Los Angeles	975 sq ft	920 sq ft	12.5% above it	HyreADU calculation
United States, all new HUD-Code homes, 2025	1,471 sq ft	1,343 sq ft	Above it	Agency published

Census Manufactured Housing Survey, average and median square feet of floor area by region, 2025, retrieved 2026-09-07 (Census disclosure-avoidance approval ID CBDRB-FY26-0220).

The West region is not California, and manufactured-home floor area is not ADU floor area — this row set exists to show the size of the product line, not to describe California ADUs.

The single-section line is the one that fits: its West average of 944 sq ft sits 24 square feet above the Los Angeles median new ADU.

Which of the three prefab legal regimes a factory unit is in — and it is in exactly one — is the subject of the prefab digest and the building-standards study.

Figures we will not repeat

An “average ADU size” for California, or for the United States
No agency publishes a floor-area distribution for California ADUs. HCD’s Annual Progress Report Table A2 counts units; it has no square-footage column. The Census Building Permits Survey has no ADU category at all.
Every national “average ADU is about 600 square feet” we have traced terminates in a builder’s page. We publish a Los Angeles median of 920 sq ft and label the geography on the row.
A recorded permit area presented as a finished building
The square_footage field is what the applicant declared and the department accepted.
It is not a survey of built floor area, it does not distinguish conditioned from unconditioned space consistently, and on alteration permits it can describe scope rather than the unit.
That is why the frame here is new construction only, and why we drop out-of-range values rather than winsorise them into the median.
The 800 sq ft number as a size allowance
§ 66321 is a constructability rule, not a grant. It says local development standards may not prevent an 800-square-foot unit with four-foot side and rear setbacks from being built.
It does not entitle anyone to 800 square feet in defiance of the other rules, and it is not the maximum either — the detached maximum is 1,200 under § 66314(a)(5).
A size recommendation dressed as a statistic
The modes in this distribution are where rules stop, not where households are best served. “Most people build 1,200” is a description of a legal ceiling.
Whether 1,200 square feet is right for your lot depends on setbacks, coverage, parking, fire access, the service capacity of the property, and what you are actually going to do with the unit. HyreADU does not design buildings.

Citing these figures

Journalists and planning desks are welcome to cite these tables. Link the size-distribution study rather than this digest: the frame rules, the dropped records and the limits live there.

Where a figure is labeled HyreADU calculation, attribute it to HyreADU and name the file — “HyreADU analysis of the Los Angeles Department of Building and Safety permit extract pi9x-tg5x, 8,536 new-construction ADU permits, 2020–2026.” Where it is Agency published, cite the Government Code section or the Census table; we are repeating it. Corrections go on the page with a dated note: hello@hyreadu.com.

Please carry the geography. Every own-calculation row on this page says City of Los Angeles. A citation that drops that word turns a defensible one-city measurement into a national claim nobody can support, which is the failure mode this whole page exists to avoid.

Questions

What is the average size of an ADU?

For new-construction ADU permits in the City of Los Angeles issued 2020–2026, the median is 920 sq ft and the mean is 975 sq ft, across 8,536 permits (HyreADU calculation). Median floor area is 480 sq ft for a garage conversion and 409 sq ft for a junior ADU. There is no sourced California-wide or national ADU size average — no agency publishes a file that would support one, and we will not manufacture one from a single city.

How big can an ADU be in California?

A detached ADU may not exceed 1,200 square feet of total floor area (Government Code § 66314(a)(5)). An attached ADU is capped at 50 per cent of the existing primary dwelling (§ 66314(a)(4)). Separately, § 66321 prevents a local agency’s development standards from defeating an 800-square-foot unit with four-foot side and rear setbacks. A junior ADU is capped at 500 square feet of interior livable space (§ 66313). Local ordinances may set lower maximums only within what the state statute allows — check your city, and check the section numbers, which changed on 1 January 2026.

Why do so many permits sit at exactly 1,200 square feet?

Because 1,200 is the statutory detached cap. 635 permits in the file are recorded at exactly 1,200 square feet and 1,061 fall in the last five square feet below it, while the bin immediately above holds 79 — 7% of the modal bin. That is a design response to a legal ceiling, not a household preference clustering by coincidence. HyreADU calculation over the LADBS extract.

What size ADU avoids impact fees?

Government Code § 66311.5 bars a local agency, special district or water corporation from imposing any impact fee on an ADU of 750 square feet or less of interior livable space, or a junior ADU of 500 square feet or less. Above 750 square feet, impact fees are charged proportionately to the square footage of the primary dwelling. Note what the same section does not waive: connection fees and capacity charges are a different pocket and are not covered — see the utility connection digest.

Is the typical ADU getting bigger?

Barely, in the middle. In the Los Angeles file, the median moved -66 square feet between 2020 and 2026 while the 90th percentile moved +617. The 75th percentile sat within a few square feet of 1,200 in every year of the window. So the center of the distribution is pinned by the cap and the growth is entirely in a thin upper tail. HyreADU calculation.

How does ADU size vary across a city?

More than most people expect. Across the seven Los Angeles area planning commissions, median permitted floor area spans 377 square feet — from 727 sq ft in West Los Angeles to 1,104 sq ft in North Valley — under one state statute and one municipal code. Lot size and parcel geometry are doing that, not law. HyreADU calculation.

Can I just buy a manufactured home and use it as an ADU?

Legally, an ADU may be a manufactured home: Government Code § 66313 includes a manufactured home as defined in Health and Safety Code § 18007. Practically, the size of the product line is the obstacle. The average new HUD-Code manufactured home shipped in the Census West region in 2025 was 1,369 sq ft — 169 square feet above California’s 1,200-square-foot detached ADU cap. Only the single-section line, averaging 944 sq ft, sits comfortably inside it. The legal regimes are set out on the prefab standards study.

Where does this data come from, and can I check it?

The City of Los Angeles Department of Building and Safety publishes every issued building permit as an open Socrata resource (pi9x-tg5x). We downloaded the full resource — 409,619 rows — on 2026-09-05, framed it on the department’s own adu_changed and junior_adu flags, dropped supplemental permits, and computed everything here from the square_footage field. The frame rules and every exclusion are written out on the size-distribution study. You can download the same file.

Written and audited by

HyreADU Research Desk

Primary-source research, data analysis and fact checking

We are a research desk, not a builder. We read the permit extract, the statute, the HCD return or the fee schedule ourselves, and publish each figure with its source and retrieval date.

Where a number cannot be traced to a primary source, we leave it out and say what we could not verify. Our store-based claims cover California only.

CA: the only state this desk will make store-based claims about
5: jurisdictions with extracted ADU permit evidence
735: CSLB-verified companies in the California store
0: national claims from a one-state store

How this desk works

Primary sources only. Permit counts come from the city or county that issued the permit. Production counts come from HCD’s Annual Progress Report. Rents come from HUD or the Census. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
This is a California site. The company store is 734 California firms and one New Mexico firm. Permit evidence exists for five named jurisdictions: Los Angeles, San Francisco, Sacramento, San José and unincorporated Marin. A number from that store is titled to those places, never to the United States.
A permit is not a completion, and a license is not an ADU grade. California licenses no ADU classification. Being named on an ADU permit is evidence of engagement in that jurisdiction, not of quality, completion, or work anywhere else. Owner-builder permits are excluded from contractor counts.
Calculation is labeled as calculation. Figures we derive are never presented as something HCD, HUD, the Census or a city published. Terner Center research is cited as Terner’s, never restated as ours.
We do not design, permit or build ADUs, and we take no payment for placement, ranking or a favorable mention. Pages that look like rankings are not: they publish public-record counts and let the reader decide.
Nothing here is legal, tax or financial advice. Zoning, underwriting and appraisal practice vary by jurisdiction, lender and appraiser. The useful next step on a specific lot is the planning counter and a licensed professional.

Data as of LADBS Socrata resource pi9x-tg5x (409,619 rows) analyzed 2026-09-05, departmental refresh to 2026-08-30; Government Code §§ 66311.5, 66313, 66314 and 66321 retrieved 2026-09-05; Census Manufactured Housing Survey annual tables retrieved 2026-09-07. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold.

Our editorial policy sets out how we source, date and correct what we publish.

Sources & retrieval dates

City of Los Angeles Department of Building and Safety — Building Permits Issued from 2020 to Present (Socrata resource pi9x-tg5x) , Full resource download, 409,619 rows, retrieved 2026-09-05; departmental refresh field to 2026-08-30. Fields used: permit_nbr, permit_type, issue_date, square_footage, apc, adu_changed, junior_adu. Every figure on this page classed as a HyreADU calculation is computed from this file. Retrieved 2026-09-05.
California Government Code § 66314 — maximum standards for an ADU , “The total floor area for a detached accessory dwelling unit shall not exceed 1,200 square feet” at (a)(5); the 50 per cent proportional cap for attached units at (a)(4). Retrieved 2026-09-05.
California Government Code § 66321 — size standards a local agency may and may not impose , The 800-square-foot constructability requirement, and the 850 / 1,000 square foot maximums. Amended by Stats. 2025, Ch. 520 (SB 543), effective 1 January 2026. Retrieved 2026-09-05.
California Government Code § 66311.5 — impact fees and the 750 square foot threshold , No impact fee on an ADU of 750 sq ft or less, or a junior ADU of 500 sq ft or less; proportional charging above. Added by renumbering § 66324 by Stats. 2025, Ch. 520 (SB 543), effective 1 January 2026. Retrieved 2026-09-05.
California Government Code § 66313 — definitions, including the 500 square foot junior ADU , “No more than 500 square feet of interior livable space … contained entirely within a single-family residence.” Also the provision that an ADU may be a manufactured home as defined in Health and Safety Code § 18007. Retrieved 2026-09-05.
SB 543 (McNerney, 2025) — Accessory dwelling units. Stats. 2025, Ch. 520 , The renumbering that moved § 66324 to § 66311.5, § 66327 to § 66313.5 and § 66332 to § 66311.7 from 1 January 2026, and amended § 66321. Cited so a reader can check why these section numbers differ from most published ADU pages. Retrieved 2026-09-05.
U.S. Census Bureau, Manufactured Housing Survey — Average and Median Square Feet of Floor Area by Region, 2014–2025 , Census disclosure-avoidance approval ID CBDRB-FY26-0220. Printed here as the size of the HUD-Code product line, not as ADU floor area. West region, 2025: all sizes 1,369 sq ft average, single-section 944 sq ft, double-section 1,532 sq ft. Retrieved 2026-09-07.
Chapple, Ganetsos and Lopez, Implementing the Backyard Revolution (UC Berkeley Center for Community Innovation, 22 April 2021) , 61 per cent of new California ADUs one-bedroom, 18 per cent studios, in a survey of owners of units permitted or completed in 2018–19. Cited as theirs, never restated as ours. Retrieved 2026-09-05.

A median is not a design

920 sq ft is what Los Angeles permits, not what your lot allows. Setbacks, coverage, fire access and service capacity decide your envelope before any statewide number does.

Size envelope calculator Read the study

HyreADU does not design, permit or build accessory dwelling units. Statistics are informational. They are not legal, construction or land-use advice, and they are not an assurance that any size is permittable on any particular lot.

Every figure labeled as a HyreADU calculation is a measurement of City of Los Angeles building permit records and describes no other jurisdiction.

Permitted floor area is a declared value accepted by a plan checker, not a survey of a finished building.

Statutory text was retrieved on the date shown; California ADU law was recodified twice between 2024 and 2026 and section numbers change.