Ontario — Zoning

Last reviewed: July 3, 2026

Overview

Ontario’s zoning framework is organized in the Development Code (Divisions 5.01–6.01 and related divisions). The City adopts an official Zoning Map and a land‑use matrix that controls what uses are allowed where; detailed dimensional and design rules live in Division 6.01 and related divisions. Confirm permitted uses in the City’s Land Use Matrix and check overlay districts and special standards before designing a project (§ 5.01.010; § 5.02 and Table 5.02‑1).

Note: this page covers only what the Ontario Development Code (zoning) says about zoning, not building-code requirements (see the California Building Standards Code).

How Ontario’s zoning is structured (quick map)

• The City adopts a single official Zoning Map and ties district rules to that map; the map is maintained in the Planning Department (§ 5.01.010).
• Allowed/prohibited uses are listed in the Land Use Matrix (Table 5.02‑1) and implemented by the base zoning districts (§ 5.02 and Table 5.02‑1) — if an activity is not listed, it’s generally prohibited unless the Zoning Administrator determines otherwise (§ 5.02).
• District standards (setbacks, height, coverage, etc.) are in Division 6.01 and in the tables referenced there (e.g., Table 6.01‑1 and Table 6.01‑3) (§ 6.01.010; Table 6.01‑3).

Because readers frequently need site‑level answers, the district writeups below (residential, commercial, industrial, mixed‑use, open space, special) name the actual Ontario districts and point to the controlling sections.

District-by-district breakdown

Notes common to all district entries: permitted/conditional/administrative uses are listed in Table 5.02‑1 (Land Use Matrix); dimensional and development rules are in Division 6.01 (District Standards and Guidelines) and related sections. Verify allowed uses against Table 5.02‑1 and any applicable overlay (§ 5.02; § 6.01).

Residential districts (overview)

• Purpose: reserve areas for a range of single‑ and multi‑family housing types and set densities, design, and open‑space rules (§ 6.01.010).
• Uses: residential primarily; accessory uses where allowed in Table 5.02‑1. See small‑lot and historic exceptions in Division 6.01 and Division 7.01 (§ 6.01.010; Division 7.01).

Subdistricts (examples — each entry: purpose / typical uses / key dimensional points / where it applies):

• LDR‑5 (Low Density Residential — 2.1 to 5.0 DU/Acre)
  Purpose: suburban single‑family neighborhoods. Typical uses: detached single‑family dwellings and allowed accessory uses per Table 5.02‑1. Key standards: subject to the single‑family development standards in Table 6.01‑1 (setbacks, lot coverage, lot size) and to small‑lot rules where applicable (§ 6.01.010; Table 6.01‑1). Verify front/side/rear setbacks in Table 6.01‑1 and § 6.01.

• MDR‑11 / MDR‑18 / MDR‑25 (Medium Density tiers: e.g., MDR‑18 = 11.1–18.0 DU/Acre; MDR‑25 = 18.1–25.0 DU/Acre)
  Purpose: attached and detached housing at increasing densities; typical uses include townhomes, duplexes, low‑rise apartments. Density bands are explicit in the district descriptions; dimensional standards are in Table 6.01‑3 (multiple‑family standards) (§ 5.01.*; Table 6.01‑3).

• HDR‑45 (High Density Residential — 25.1 to 45.0 DU/Acre)
  Purpose: higher‑intensity multi‑family, typically near transit corridors. Key rules: density limits spelled out in the district description and design guidance in Division 6.01; proximity to transit may trigger additional standards (§ 5.01.*; § 6.01).

Practical: accessory dwelling units (ADUs) are regulated elsewhere; check the City ADU page and State ADU law if you plan an ADU in any residential district (see Ontario ADUs and California ADU law).

Commercial districts

• CS (Corner Store) — small pedestrian‑oriented neighborhood retail; maximum FAR 0.4; intended for sites typically < 0.5 acre. See district purpose and human‑scale expectations (§ 5.01.*).
• CN (Neighborhood Commercial) — maximum FAR 0.4; supports convenience centers serving 1–2 mile radius; hours/uses may be limited near residences (§ 5.01.*).
• CC (Community Commercial) — maximum FAR 0.4; larger retail/office/service uses serving up to ~5‑mile radius; may be limited near residential adjacencies (§ 5.01.*).
• CR (Regional Commercial) — maximum FAR 0.4; intended for regional‑serving centers, often adjacent to freeways; specific constraints apply for auto‑dealer uses (freeway frontage requirements) (§ 5.01.*).

Typical requirements for commercial projects (parking, setbacks, screening) point to Division 6.01 and off‑street parking rules in Division 6.03 — always check the Ontario Parking rules and the Ontario Development Standards pages.

Mixed‑use, downtown, and specialized districts

• MU‑1 (Downtown Mixed Use) — accommodates mixed commercial/residential downtown forms; some uses (e.g., alcoholic beverage manufacturing or bars) have special conditional rules and area limitations identified in Division 5.03 and Table 5.02‑1 (§ 5.03.023; Table 5.02‑1).
• PUD (Planned Unit Development) — master‑planned projects requiring a specific PUD document; follow the PUD adoption and design rules (§ 5.01.*).
• SP (Specific Plan) — properties in SP must be developed under an adopted specific plan; absent a plan, a new specific plan or annexation is required before permits (§ 6.01.*).

Industrial districts and airport areas

• IG / IH (Industrial General / Heavy Industrial) — industrial uses and ancillary functions; when the ONT (Ontario International Airport) zoning district applies, IG standards are generally used with some special FAR and deviation authority for airport area projects (§ 5.03.020).
• ONT (Ontario International Airport) Zoning District — adopts IG standards with special FAR calculation and Planning Director authority to deviate from landscape/setback/height where site conditions require (§ 5.03.020.A).

Open space, public, and utility districts

• OS‑R (Open Space‑Recreation) and OS‑C (Open Space‑Cemetery) — parks, recreation, and cemeteries; development follows the standards applicable to comparable commercial/open‑land districts (§ 6.01.*).
• UC (Utilities Corridor) — flood control, transmission corridors, retention basins; ancillary trail uses allowed and standards reference OL/OL‑type rules (§ 6.01.*).

Overlay and specialized overlays (where they apply)

Ontario uses several overlay districts that modify base zoning:

• AG (Agriculture) Overlay — interim agricultural uses over underlying zoning (§ 5.01.*).
• EA (Euclid Avenue) Overlay — protects Euclid Avenue’s historic character (NRHP recognition) and applies design rules for that corridor (§ 5.01.*).
• ES (Emergency Shelter) Overlay — accommodates emergency shelters, supportive/transitional housing consistent with the Housing Element (§ 5.01.*).
• MTC (Multimodal Transit Center) Overlay, ICC (Interim Community Commercial), AH (Affordable Housing), CNO (Chino Airport) — each overlay carries its own applicability and cross‑references in Division 5.01/6.01; overlay rules control uses, compatibility, and additional review requirements (§ 5.01.*; § 6.01.035).

Check the Ontario Overlay Districts page for project‑specific impacts and the Development Code’s overlay section (§ 6.01.035).

Key decision table (most decision‑relevant standards / uses)

Checklist

• Confirm the property’s zoning district on the City Zoning Map (§ 5.01.010).
• Verify whether any overlay district (AG, EA, ES, MTC, ICC, AH, CNO, ONT, etc.) applies (§ 6.01.035; § 5.01.*).
• Confirm whether the proposed use is Allowed / Conditional / Administrative / Prohibited in Table 5.02‑1 (Land Use Matrix) (§ 5.02).
• Pull the district dimensional standards (setbacks, height, lot coverage, FAR, density) in Division 6.01 (Table 6.01‑1 / Table 6.01‑3) and off‑street parking in Division 6.03 (Ontario Parking).
• Determine whether alterations require an Administrative Use Permit, Conditional Use Permit, or Design Review (see § 4.03.015 and Ontario Design Review).
• If the lot or use is nonconforming, check Division 3.01 rules before changes (§ 3.01.*; see Ontario Nonconforming Uses).
• For projects touching historic resources, apply Division 7.01 requirements and consult Ontario Historic Preservation.

Risks & Ambiguities

Plain‑English Summary

Ontario’s Development Code ties every parcel to a named zoning district shown on the official Zoning Map; allowed uses come from the Land Use Matrix (Table 5.02‑1), and dimensional/design rules come from Division 6.01 and overlay provisions. Always check the Zoning Map, Table 5.02‑1, Division 6.01 standards, and any overlay that applies before designing a project — if something’s not listed, ask Planning for a formal land‑use determination (§ 5.01.010; § 5.02; § 6.01.035).

Source References

• § 5.01.010 Zoning Map Adoption — official map maintained by Planning Department.
• § 5.01.015 Zoning District Boundaries — rules for interpreting map lines (centerlines, lot lines).
• Division 5.01 — Zoning Districts and Boundaries (district descriptions: CS, CN, CC, CR, MDR‑18, MDR‑25, HDR‑45, etc.).
• Table 5.02‑1 (Land Use Matrix) and Division 5.02 — establishes permitted/conditional/admin uses and NAICS mapping.
• § 5.03.020 ONT (Airport) and related airport standards; § 5.03.023 (alcoholic beverage/manufacturing rules in MU‑1).
• Division 6.01 — District Standards and Guidelines (Table 6.01‑1, Table 6.01‑3, small‑lot infill rules, setbacks, etc.).
• Division 3.01 — Nonconforming Lots, Uses and Structures (repair/expansion/abatement rules).
• Division 5.03 — Supplemental Land Use Regulations (Urban Farms, adult‑oriented businesses, alcoholic beverage manufacturing, etc.).
• Overlay district summaries (AG, EA, ES, MTC, ICC, AH, CNO) and overlay applicability § 6.01.035.

Retrieved passages

• Ontario Zoning Code High relevance show source text
• Ontario Zoning Code High relevance show source text
• Ontario Zoning Code (Section 6.02.020) High relevance show source text
• Ontario Zoning Code (Section 4.03.015) High relevance show source text
• Ontario Zoning Code (Section 6.02.020) High relevance show source text
• Ontario Zoning Code High relevance show source text
• Ontario Zoning Code (Section 4.02.040) High relevance show source text
• Ontario Zoning Code (Title 4) High relevance show source text

Cited sections

• § 5.01.010 Zoning Map Adoption — official map maintained by Planning Department. (§ 5.01.010)
• § 5.01.015 Zoning District Boundaries — rules for interpreting map lines (centerlines, lot lines). (§ 5.01.015)
• Division 5.01 — Zoning Districts and Boundaries (district descriptions: **CS, CN, CC, CR, MDR‑18, MDR‑25, HDR‑45**, etc.).
• Table 5.02‑1 (Land Use Matrix) and Division 5.02 — establishes permitted/conditional/admin uses and NAICS mapping.
• § 5.03.020 ONT (Airport) and related airport standards; § 5.03.023 (alcoholic beverage/manufacturing rules in MU‑1). (§ 5.03.020)
• Division 6.01 — District Standards and Guidelines (Table 6.01‑1, Table 6.01‑3, small‑lot infill rules, setbacks, etc.).
• Division 3.01 — Nonconforming Lots, Uses and Structures (repair/expansion/abatement rules).
• Division 5.03 — Supplemental Land Use Regulations (Urban Farms, adult‑oriented businesses, alcoholic beverage manufacturing, etc.).
• Overlay district summaries (AG, EA, ES, MTC, ICC, AH, CNO) and overlay applicability § 6.01.035. (§ 6.01.035.)
• Ontario_ZoningCode.md

• Official Ontario code library