Most studios legally house one or two people. The exact number allowed in your studio apartment depends on three overlapping rules: the local building or housing code, federal fair housing guidance from HUD, and whatever your lease says. In the vast majority of cases, all three point to the same answer.
Square Footage Sets the Floor
The International Property Maintenance Code, a model code adopted in some form across most of the country, sets minimums for what it calls an “efficiency unit.” Up to two occupants requires at least 220 square feet of clear floor space. A third person pushes the requirement to 320 square feet. Any room used for sleeping by more than one person must provide at least 50 square feet per occupant.
The average American studio runs roughly 450 to 500 square feet, which clears the two-person threshold comfortably. Size alone doesn’t settle it, though. Your city or county may have adopted the IPMC directly, modified it, or written its own occupancy rules. The code that actually governs your unit is the one your local government has enacted. You can usually find it by searching your city’s name plus “property maintenance code” or “housing code” on the municipal website.
Ceiling height matters too. Under federal residential standards, every habitable room must have a ceiling of at least seven feet across at least half of the floor area.1eCFR. 24 CFR 3280.104 – Ceiling Heights A lofted sleeping nook with a four-foot ceiling doesn’t count toward habitable square footage, which can shrink the usable footprint and pull you below an occupancy minimum you thought you cleared.
HUD’s Two-Per-Bedroom Guidance
Federal occupancy guidance comes from what’s commonly called the Keating Memo, issued in 1991 and formally adopted as HUD policy in 1998. The memo established a benchmark: two people per bedroom is generally reasonable under the Fair Housing Act.2Department of Housing and Urban Development. Fair Housing Enforcement – Occupancy Standards Statement of Policy The standard exists to evaluate discrimination complaints, not to cap occupancy in any specific unit.
HUD stressed that the reasonableness of any policy depends on bedroom size, overall unit size, building configuration, and state or local law.2Department of Housing and Urban Development. Fair Housing Enforcement – Occupancy Standards Statement of Policy A landlord who restricts a spacious unit more tightly than the building code allows draws more scrutiny than one whose limit tracks the code.
Studios sit awkwardly in this framework because the Keating Memo doesn’t specifically address zero-bedroom units. With no separate bedroom, the “two per bedroom” formula doesn’t map cleanly. In practice, most landlords and housing authorities treat two occupants as the reasonable ceiling for a standard studio, drawing on HUD’s broader point that overall dwelling size matters. That’s an inference, not an explicit HUD rule for studios.
What Your Lease Can Add
Your landlord can set occupancy limits stricter than the building code. A studio that meets the square-footage threshold for three people under local code might still carry a two-person cap in the lease. That’s common and generally legal. Landlords have a legitimate interest in managing wear on the unit and keeping utility costs predictable.
The limit has to be applied uniformly across similar units. A landlord who caps one studio at two people but allows three in an identical unit down the hall is inviting a discrimination complaint. The restriction also can’t be a pretext for excluding families or any other protected group.
Some leases include a surcharge for adding an occupant, framed as covering extra utility or maintenance costs. These charges are generally permissible when they’re reasonable, disclosed in the lease, and applied the same way to every tenant. If you’re thinking about adding someone, read the lease before they move in, not after the landlord notices.
Children and Families
The Fair Housing Act makes it illegal to discriminate based on familial status, which covers families with children under 18, pregnant individuals, and anyone in the process of gaining custody of a child.3Office of the Law Revision Counsel. 42 USC 3604 – Discrimination in the Sale or Rental of Housing A landlord cannot refuse to rent you a studio because you have a toddler, and a blanket “no children” policy is illegal.
Familial status protections don’t override reasonable occupancy limits. The Fair Housing Act itself preserves the right of local, state, and federal authorities to set maximum occupancy restrictions.4Office of the Law Revision Counsel. 42 USC 3607 – Religious Organization or Private Club Exemption A landlord can enforce a legitimate, uniformly-applied two-person limit in a studio even when one of those two people is a child.
Where the law draws the line is using occupancy rules against families. Telling a couple they need to move out because they had a baby, especially when the unit is still within a reasonable occupancy range, would face heavy scrutiny from HUD. Infants are generally not counted as full occupants for overcrowding purposes, and no national rule specifies the exact age at which a child starts to count. Enforcement in this area is fact-specific, and landlords who push too hard against new parents risk a discrimination complaint.
When a Guest Becomes an Occupant
Most leases cap guest stays somewhere between 10 and 14 consecutive days, though the exact limit varies. Beyond the calendar, what really separates a guest from an unauthorized occupant is behavior. Landlords and courts look at whether the person receives mail at the address, whether they’ve listed the unit on an ID or driver’s license, whether they contribute to rent or utilities (which can establish a landlord-tenant relationship in many jurisdictions), and whether they’ve moved in furniture or belongings beyond an overnight bag.
An unauthorized occupant can put you in violation of your lease’s occupancy limit even when you’re still under the building code maximum. The lease governs what your landlord can enforce, and an undisclosed resident is one of the easier violations to prove. Most landlords have a process for adding someone to the lease, typically a background check and sometimes an application fee. Handling it up front is cheaper than fighting a lease violation later.
What Happens If You Exceed the Limit
If your landlord discovers more people in the unit than the lease allows, the first step is usually a written notice giving you a set number of days to either reduce the number of occupants or, if the landlord agrees, add the extra person to the lease. This cure period varies by jurisdiction but commonly falls between 7 and 30 days.
Ignore the notice and the landlord can file for eviction. Courts routinely uphold these cases when the limit was clearly stated in the lease and applied consistently. “I didn’t know” is not a defense that tends to work; the occupancy clause is in the document you signed.
Overcrowding can also draw problems from outside the landlord relationship. Local code enforcement can inspect and cite a unit that exceeds municipal occupancy limits. In serious cases, a government agency can order the unit vacated until the violation is corrected, which leaves you scrambling for housing on short notice.
For most people in a studio, the math is simple. Two adults is almost always fine. Three requires a large unit and a cooperative landlord. Anything beyond that is unlikely to survive scrutiny from any direction.