What Is R-3 Zoning? Low-to-Medium Density Multifamily Districts Explained

R-3 is where multifamily usually begins. In most codes it is the district that allows townhouses, triplexes, and small apartment buildings by right, at a density and height that still fit next to single-family neighborhoods. The exact density varies widely, which is what makes R-3 land worth reading carefully.

What R-3 usually allows

• Single-family and two-family dwellings.
• Townhouses and rowhouses.
• Multifamily buildings, from triplexes to garden apartments, up to the district's density limit.
• Group housing, small institutional uses, and civic uses, often conditionally.

Commercial uses are generally excluded except small home occupations and, in some codes, live-work units.

What the code usually requires

• Density: expressed as units per acre (commonly 12 to 30) or as minimum lot area per unit (commonly 1,500 to 3,600 square feet per unit).
• Height: two and a half to four stories, often 35 to 45 feet.
• Setbacks, lot coverage, and open space per unit.
• Parking: one to two spaces per unit, reduced or eliminated near transit in reform-minded cities.
• Design and compatibility standards on edges adjoining single-family districts.

How real cities define R-3

• Detroit: R3 is the Low Density Residential District, which brings in townhouses and small multifamily buildings above R2's two-family limit. See our Detroit zoning guide.
• Phoenix: R-3 is a Multi-Family Residence District in the middle of the multifamily range, with R-3A, R-4, R-4A, and R-5 above it. See our Phoenix zoning guide.
• Los Angeles: R3 is the Multiple Dwelling Zone, allowing apartments at a lot-area-per-unit standard that yields moderate density.
• New York City: R3 districts (R3-1, R3-2, R3A, R3X) are low-density districts allowing detached, semi-detached, and, in R3-2, small multifamily buildings, so NYC's R3 is lower density than most cities' R-3.
• Austin uses MF-1 through MF-6 for multifamily rather than R-3; MF-2 and MF-3 are the rough equivalents. See our Austin zoning guide.

What you can typically build

Townhouse rows, small walk-up apartment buildings, and, on larger sites, garden apartment communities. The yield is set by the density rule, then trimmed by parking, open space, and setbacks. A four-acre R-3 parcel at 20 units per acre is 80 units on paper; whether it is 80 units on a site plan depends on the parking ratio.

Developers look for R-3 parcels that are under-built (a single house on a multifamily lot), assemblable, or adjacent to corridors where an R-4 or mixed-use rezoning is plausible. Our multifamily site selection guide covers the search.

How to check a specific parcel

Confirm the district on the official zoning map, then read the density, height, and parking standards in the code. In Plotzy, filter a market to R-3 and the city's equivalent designations above a lot size, and ask Zoning AI "What is the maximum density and height in R-3 here?" for an answer from the ordinance with the section cited.

Frequently asked questions

What does R-3 zoning mean?

R-3 is typically a low-to-medium density multifamily residential district allowing townhouses and small apartment buildings alongside single-family and two-family homes, subject to density, height, and parking rules that vary by city.

How many units can I build on R-3 land?

Divide the site area by the district's minimum lot area per unit, or multiply acres by the units-per-acre limit, then check parking, open space, and setbacks. Typical R-3 densities run from about 12 to 30 units per acre.

What is the difference between R-3 and R-4 zoning?

R-4 generally allows higher density or taller buildings than R-3. In some cities, such as New York and Baltimore, R-4 is still a low-density district. See our R-4 explainer.

Can I build a duplex in R-3?

Usually yes; R-3 generally permits everything allowed in R-1 and R-2 plus multifamily.