Ontario | Lot size and subdivisions
Ontario, California Lot Sizes and Subdivisions: Lot Standards, Parcel and Tract Maps, Small Lot Infill Subdivisions, SB 9 Urban Lot Splits and Small-Lot Maps
This page covers the size a lot must have in each Ontario zone and the ways to divide land. A subdivision is a division of land into lots that can be sold separately, and it is recorded on a map. The rules are in Chapters 4.0 and 6.0 of the Ontario Development Code. Ontario has four small-lot options in its own code, one of them with lots of 480 square feet, and a section on state SB 9 lot splits that is narrower than the statute on the eligible zone, home size and grounds for denial. The Ontario overview has the summary.
Ontario lots and subdivisions in six facts
- A traditional house lot in LDR-5 needs 7,200 square feet, an 8,000 square foot average across the subdivision, and 60 feet of width. Source: Development Code, Table 6.01-1
- A parcel map is required for a division into 4 or fewer lots, and a tentative tract map and final map for 5 or more. Source: Development Code 6.08.010
- The Planning Commission decides tentative maps after a hearing, and the City Council approves final maps. Source: Development Code, Table 2.02-1
- A Small Lot Infill Subdivision may create lots of 480 square feet and 16 feet of width, with no more than 45 homes. Source: Development Code 6.01.010.G
- The City section on SB 9 urban lot splits covers LDR-5 lots of at least 2,400 square feet, with new lots of at least 1,200 square feet and 20 feet of street frontage. Source: Development Code 6.08.060
- The Planning fee for a Tentative Parcel Map is $13,469.53, and Engineering charges $12,580 plus $220 per lot to review a final map. Source: Planning Department Fee Schedule
Lot Standards by Zone
| Zone | Minimum lot | Average lot | Interior width | Corner width | Depth |
|---|---|---|---|---|---|
| AR-2 | 18,000 sq ft | None printed | 100 ft | 120 ft | 135 ft |
| RE-2 | 10,000 sq ft | 18,000 sq ft | 70 ft | 80 ft | 100 ft |
| RE-4 | 10,000 sq ft | None printed | 70 ft | 80 ft | 100 ft |
| LDR-5 | 7,200 sq ft | 8,000 sq ft | 60 ft | 65 ft | 75 ft |
| MDR-11, MDR-18, MDR-25 and HDR-45 | 5,000 sq ft | 6,000 sq ft | 50 ft | 50 ft | 100 ft |
Source: Ontario Development Code, Section 6.01.010, Table 6.01-1, Traditional Single-Family Residential Development Standards (Rev. 08.18.2026). A cul-de-sac lot needs 40 feet at the front property line in every zone.
These are the standards for a traditional single-family lot, one detached house on its own lot. The average column means the lots of a subdivision, taken together, must average that size. Three more rules sit beside the table.
- No lot may be cut below the minimum. "No lot or parcel shall be reduced in area to less than the minimum area prescribed for the district in which the site is located, unless a Variance is granted."
- Lots that are already small. Section 3.01.010 calls a lawfully created lot below the standards a "legal nonconforming lot" and says it "shall be granted all development rights and land uses of the zoning district in which it is located."
- Lots from before 1947. "Any lot that is shown on a recorded map prior to November 5, 1947, and that had a legal area, width, and frontage at the time the subdivision map was recorded or the lot was legally created, may be used for an allowed land use."
- Access. "All residential, commercial, mixed use, and industrial lots shall have direct access to a public street, except where private street, common driveway or other access easement rights are specifically approved by the City."
Four Small-Lot Options in the City Code
| Type | Minimum project | Minimum lot | Lot dimensions | Lot coverage |
|---|---|---|---|---|
| Small lot traditional, LDR-5 and MDR-11 | One acre | 4,000 sq ft interior, 4,500 corner | 40 ft wide (45 corner), 75 ft deep | 55% in LDR-5, 60% in MDR-11 |
| Small lot traditional, MDR-18, MDR-25 and HDR-45 | One acre | 2,800 sq ft interior, 3,200 corner | 35 ft wide (40 corner), 70 ft deep | 70% |
| Small lot alley-loaded | One acre, 200 ft by 200 ft | Set by width and depth | Same widths and depths as small lot traditional | 55%, 60% or 70% by zone |
| Cluster single-family (3 or more detached homes) | One acre, 200 ft by 200 ft | None | None | None |
| Small Lot Infill Subdivision (up to 45 homes) | None printed | 480 sq ft | 16 ft wide | 80% per lot, or 20% common open space |
Source: Ontario Development Code, Section 6.01.010, Tables 6.01-2A, 6.01-2B and 6.01-2C and Subsection G (Rev. 08.18.2026).
The first three types need a project of one acre, so they suit a builder with a large site. A note to each table lets an existing lot below one acre use the type, "except that the maximum density shall be limited to the minimum allowed within the density range." The zoning districts page shows which zones the Land Use Matrix permits for each type; the matrix and the tables differ for LDR-5.
The fourth type is the one designed for a single infill lot. Subsection G describes it as "infill small lots as an alternative form of fee simple homeownership." Fee simple means each buyer owns the land under the home. Its main rules:
- Size of the project. "A Small Lot Infill Single-Family Subdivision shall contain no more than 45 dwelling units," and the density must follow the underlying zone.
- Size of each lot. Each lot "shall have a minimum area of 480 SF and a minimum lot width of 16 FT."
- Coverage or shared open space. A lot may be covered up to 80 percent. As another choice, the project may give common open space "equal to at least 20 percent of the total subdivision area," with at least 50 square feet of private open space for each home.
- Setbacks. "No front, side, or rear yard setback is required between interior lots," and a 5-foot setback applies where a lot meets land outside the project. Next to LDR-5 or denser residential land, the edge of the project follows the setbacks of the underlying zone.
- Height and spacing. "the maximum allowed building height is 40 FT," with at least 6 feet between buildings and 10 feet in front of a home's main entry.
- Parking. 1.0 space for each bedroom plus 0.2 guest space for each bedroom, with at least one space in an enclosed garage. Tandem parking, one car behind another, is allowed up to two cars deep.
- Rows of homes. Homes are grouped in rows of no more than six units or 180 feet, with a 6-foot gap between groups.
- Existing homes. A lot that already holds two or more detached houses or a historic bungalow court "may be subdivided" under the same subsection.
Which Map a Division Needs
- Parcel map. Section 6.08.010 requires a parcel map "for all subdivisions creating 4 or fewer lots, or 4 or fewer condominium units."
- Tract map. "A tentative tract map and final map shall be required for all subdivisions creating 5 or more lots, 5 or more condominium units," and for the matching community apartment and stock cooperative projects.
- Condominiums and other shared-ownership projects. Section 6.08.045 says common interest subdivisions "shall be exempt from the minimum lot area and building setback regulations applicable to individually numbered and/or lettered lots." The lot area rule is applied to the whole project, and setbacks to its outer edge.
- Parcel map waiver. The City Engineer may waive the final parcel map for a division made by probate, eminent domain or a court judgment, or for land conveyed to a public agency.
- State law controls a conflict. "In the event of a conflict between any mandatory provision of the Subdivision Map Act and a provision of this Division, the Subdivision Map Act shall control."
How a Tentative Map Is Decided
A tentative map is the first drawing of the new lots, reviewed before any survey is recorded. Table 2.02-1 sends tentative tract maps, tentative parcel maps and vesting maps to the Development Advisory Board for a recommendation and to the Planning Commission for the decision, with appeal to the City Council. A public hearing is required. Notice is mailed at least 10 days ahead to owners "within 600 FT of the exterior boundaries of the property."
- Findings. Section 4.02.095 lists seven findings. Two of them are that "The site is physically suitable for the type of development proposed" and that "The site is physically suitable for the proposed density of development." The map is denied if one finding cannot be made.
- Who draws it. Tentative maps "shall be prepared by a state-licensed land surveyor or state-registered civil engineer authorized to practice land surveying" and carry a map number from the San Bernardino County Surveyor.
- How long it lasts. Section 2.02.025 says a tentative map "shall become invalid if not exercised within the time limits specified by GC Section 66452.6." That statute says "An approved or conditionally approved tentative map shall expire 24 months after its approval or conditional approval," unless extended. A map is exercised when the final map is recorded with the County Recorder.
- Appeals. An appeal is filed "within 10 days following the action or decision being appealed." For a tentative map the appeal reaches the City Council within 30 days, and the Council decides within 10 days after its hearing.
- Small changes. Changes "affecting less than 20 percent of the total number of lots in the subdivision" with no added lots may be processed by staff with no hearing.
The Planning Department fee schedule of August 22, 2026 lists a Tentative Parcel Map at $13,469.53 and a Tentative Tract Map at a base of $19,987.07 plus $65.00 per lot or unit. A note says a public hearing or review fee is added: $401.00 for the Development Advisory Board and $746.00 for the Planning Commission.
Final Maps, Adjustments and Mergers
- Final map. The City Engineer examines a final map or parcel map "within 30 working days of receipt." The City Council then approves it at the meeting where it is received or the next regular meeting if it matches the tentative map. If the Council does not act in that time and the map conforms, "it shall be deemed approved."
- Final map fees. The Engineering Department fee schedule effective August 22, 2026 lists a Final Map review at a base of $12,580 plus $220 per parcel or lot. The fee covers three reviews.
- Lot line adjustment. Section 4.03.035 lets an owner "reconfigure up to 4 adjoining legally recognized lots" where no added parcel results. The City Engineer decides, no map is required, and the Engineering fee is $4,000 plus $64 per parcel.
- Lot merger. The City may merge adjoining lots held by one owner when a lot "Comprises less than 5,000 SF in area" or fails another listed test and at least one lot has no main building. The owner may ask for a hearing within 30 days of the notice.
- Certificate of compliance. A lot with no map behind it can be confirmed as legal by the City Engineer. The Engineering fee is $869. A two-unit project under Section 5.03.403 requires this certificate with the application.
Park Land and Park Fees
Section 6.08.030 makes a residential subdivision give park land, pay a fee, or both, "at the sole and exclusive option of the City." Land is measured at "5.0 acres of property for every 1,000 persons residing within the City," and the fee is calculated at 3.0 acres per 1,000. For an infill project the fee is the usual result: "If the subdivision contains 50 lots or less, only the payment of impact fees may be required." Park fees are paid "at the time of issuance of a building permit for each lot within the subdivision." The current amounts are on the permits and fees page.
SB 9 Urban Lot Splits: the City Section and the Statute
An urban lot split is the state right, created by SB 9, to divide one house lot into two with no hearing. Ontario's rules are Section 6.08.060, and the City Engineer approves the parcel map. The statute is Government Code 66411.7, last amended effective June 30, 2026. The pages of Section 6.08.060 print a revision date of December 1, 2020, which is before the statute first took effect, so the date tells nothing about when the City last edited the text.
| Topic | Ontario Section 6.08.060 | Government Code 66411.7 |
|---|---|---|
| Where | A lot in the LDR-5 zoning district | A parcel "located within a single-family residential zone" |
| Lot sizes | Lot to split at least 2,400 sq ft; each new lot at least 1,200 sq ft and 40 to 60 percent of the original | Each new lot at least 1,200 sq ft and at least 40 percent of the original |
| Access | Each lot adjoins a public street with at least 20 ft of frontage | A city may require that the parcels have access to or adjoin the public right-of-way |
| Home size | 500 to 800 sq ft for each primary dwelling | No standard that would "result in a unit size of less than 800 square feet" |
| Height | One story or 16 ft on a new lot of 2,000 sq ft or more; two stories or 22 ft on a smaller lot | Objective standards that do not conflict with the section |
| Who may apply | Individual property owners; no corporation, with two named exceptions | Applicant signs an affidavit to live in one unit for 3 years |
| Grounds to deny | A specific, adverse impact on public health and safety or on the physical environment | A specific, adverse impact "upon public health and safety" |
| Deadline | None in Section 6.08.060; 60 days for ministerial approvals in Section 2.02.015 | 60 days, after which "the application shall be deemed approved" |
| Tentative map life | "The tentative parcel map shall expire 3 months following approval." | No time limit in Section 66411.7 |
Sources: Ontario Development Code, Section 6.08.060 and Section 2.02.015; Gov. Code 66411.7 as amended by Stats. 2026, Ch. 56 (SB 1426).
Where a City rule is stricter than the statute allows, the statute controls. Four differences matter most for an owner.
- The zone. The City text says that, for this section, a single-family residential zoning district "shall mean the LDR-5" district. AR-2, RE-2 and RE-4 are also zones where the Land Use Matrix permits houses and prohibits multiple-family dwellings, and the statute's test is a "single-family residential zone." Ask the City whether it accepts applications in those three zones.
- Size and height of the homes. The City caps each primary dwelling at 800 square feet, and new ones on a lot of 2,000 square feet or more at one story and 16 feet. The statute bars a standard that would result "in a unit size of less than 800 square feet," so 800 square feet is the least a city must allow. The related two-unit statute bars standards "that do not apply uniformly to development within the underlying zone," and LDR-5 allows houses of 35 feet.
- Grounds to deny. The City text lets the building official deny for a specific, adverse impact "on either public health and safety or on the physical environment." The statute names public health and safety only.
- Nonconforming conditions. Here the City text matches the statute: "An Urban Lot Split may be approved without requiring a legal nonconforming zoning condition to be corrected."
Other City conditions track the statute. The lot must not come from an earlier urban lot split, and the owner must not have split the lot next door. The split may not demolish or alter rent-restricted housing or housing "that has been occupied by a tenant in the last 3 years." The lot may not be a historic property or sit in a historic district. No dedication of right-of-way or offsite improvement is required. A lot in a very high fire hazard severity zone needs a street at least 40 feet wide with two points of access, fire sprinklers and other listed measures. The owner records a deed restriction that bars rentals of less than 30 days and any nonresidential use. The homes on the new lots are covered on the ADUs and SB 9 page.
SB 684 and SB 1123 Small-Lot Maps
SB 684 and SB 1123 are state laws that make a city approve a small subdivision with no hearing. The Ontario Development Code has no section on them: a search of the ten code files saved for this guide found no mention of Government Code 66499.41, SB 684 or SB 1123. The statute applies without a local ordinance. It covers a subdivision that "will result in 10 or fewer parcels" with "10 or fewer residential units," on a multifamily-zoned lot of no more than five acres or a vacant single-family lot of no more than one and one-half acres, and it requires a decision "within 60 days from the date the local agency receives a completed application." The statute was amended effective September 30, 2026, and a new version becomes operative on January 1, 2027. Ask the Planning Department how it processes such a map and which fee it charges, because the fee schedule has no line for it.
Limits of This Page
The Chapter 6.0 file is named "Rev 08-18-2026." The pages of Division 6.08 print "Rev. 12.01.2020," and the pages of Chapter 4.0 print "Rev. 08.16.2026" and "Rev. 11.04.2025." City Council agendas from January 7, 2025 to October 6, 2026 were read, and none lists an ordinance on urban lot splits. The fee schedules have no line named for an urban lot split, a two-unit project or a small-lot map under Government Code 66499.41. The City's application forms and submittal checklists for maps were not read. The rest of the Ontario Municipal Code, outside the Development Code, is hosted by an outside publisher whose site blocks scripted requests, and it was not read.
Best For
- ✓ An infill lot in an MDR zone or HDR-45 that can be divided into fee simple lots of 480 square feet or more.
- ✓ An LDR-5 lot of at least 2,400 square feet with 40 feet of street frontage or more, for an urban lot split.
- ✓ A site of one acre or more in LDR-5 or MDR-11, where small lot traditional homes fit on 4,000 square foot lots.
Usually Fails When
- ✕ An urban lot split is planned on a lot rented to a tenant in the last 3 years.
- ✕ A lot split is filed by an LLC, which the City section excludes.
- ✕ A tentative map is left unrecorded past the life set by Government Code 66452.6.
What To Verify Before Spending Money
- → Whether the City accepts an urban lot split in AR-2, RE-2 or RE-4.
- → The home size and height limits the City applies after the 2026 amendments to the state statute.
- → How the City processes a map under Government Code 66499.41 and what it charges.
Where to Go Next
Related on VanPlex: the Ontario overview, the California SB 9 page and the SB 684 and SB 1123 page.
Frequently Asked Questions
What is the minimum lot size in the LDR-5 zone in Ontario, California?
When does a land division in Ontario need a parcel map and when a tract map?
Who approves a tentative map in Ontario, California?
How long does an approved tentative map last in Ontario?
What is a Small Lot Infill Subdivision in Ontario?
Can I split my Ontario lot under SB 9?
How small can the two lots be after an urban lot split in Ontario?
Can a company apply for an urban lot split in Ontario?
Does Ontario have rules for SB 684 small-lot subdivisions?
What does a lot line adjustment cost in Ontario?
Does a small Ontario subdivision have to give park land?
Can I build on an Ontario lot that is smaller than the zone minimum?
Official sources (checked October 2026)
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