How Many Toilets Per Person Does a Public Building Require?

Public buildings generally need one toilet for every 25 to 75 occupants, with the exact ratio set by how the building is used and calculated separately for men and women. The International Building Code and International Plumbing Code establish these minimums, and almost every U.S. jurisdiction adopts some version of them. A small office and a nightclub of the same size will land on very different fixture counts because the underlying formulas assume very different patterns of use.¹

Start With the Occupant Load

Every fixture calculation begins with the occupant load: the maximum number of people the space is expected to hold at any one time. You get there by dividing the floor area by a per-person factor tied to the use of the space. An office uses 150 gross square feet per person, a restaurant with tables and chairs uses 15 net square feet per person, and a retail store uses 60 gross square feet per person. A 15,000-square-foot office therefore has an occupant load of 100.²

The code then assumes a 50/50 male-to-female split unless you can show a different distribution. For the 100-person office, you calculate fixtures for 50 males and 50 females separately, and any fractional result rounds up to the next whole fixture.¹

Local jurisdictions routinely amend the model codes. New York City, for example, uses different fixture ratios than the base IBC. Check the version your building department has adopted before you finalize anything.

Fixture Ratios by Building Type

IBC Table 2902.1 sets the minimums for each occupancy classification. The ratios can differ sharply between building types, and male and female counts often are not the same.¹

Offices

Group B business occupancies require one male water closet per 25 males for the first 50 occupants, then one per 50 after that. Female water closets are one per 40 for the first 80, then one per 80 beyond. Lavatories are one per 100 occupants total.

For the 100-person office: 50 males need 2 water closets (50 ÷ 25), and 50 females need 2 (50 ÷ 40 = 1.25, rounded up). At least 1 lavatory covers the code, though designers usually install a sink in every restroom, so real-world lavatory counts run higher than the minimum.

Restaurants and Bars

Group A-2 restaurants need one water closet per 75 occupants of each sex. A 300-seat restaurant, with 150 per sex, needs 2 male and 2 female water closets at minimum. Nightclubs and bars use a tighter ratio of one per 40 of each sex, reflecting the heavier demand that comes with turnover and alcohol.¹

Theaters and Performance Venues

Group A-1 theaters and concert halls require one water closet per 125 males and one per 65 females. A 1,000-seat theater with 500 of each sex needs 4 male and 8 female water closets at minimum.³

Retail Stores

Group M mercantile spaces have the most relaxed ratios: one male water closet per 500, one female per 750, and lavatories at one per 1,000 total. A small shop often needs just one toilet on each side. Large shopping centers usually meet these numbers through common-area restrooms rather than fixtures in every tenant space.¹

Stadiums and Arenas

Large venues use a tiered formula. For the first 1,500 males, it’s one water closet per 75, dropping to one per 120 beyond that. For women, it’s one per 40 for the first 1,520, then one per 60. A 30,000-seat stadium ends up needing hundreds of fixtures, and small miscalculations translate into long game-day lines.¹

OSHA Requirements for Employee Restrooms

OSHA runs on a separate track from the building code. Under 29 CFR 1910.141, employers must provide a minimum number of toilets based on the head count at the worksite, and the numbers are lower than what the building code asks for in public-facing spaces:⁴

1 to 15 employees: 1 water closet
16 to 35 employees: 2 water closets
36 to 55 employees: 3 water closets
56 to 80 employees: 4 water closets
81 to 110 employees: 5 water closets
111 to 150 employees: 6 water closets
Over 150 employees: 1 additional water closet for each additional 40 employees

Facilities must be in separate rooms for each sex. A single-occupancy lockable room with at least one water closet can serve both sexes. Where only men will use the facilities, urinals can replace some water closets, but the number of water closets can’t drop below two-thirds of the table minimum.⁴

Urinal Substitution Limits

Urinals reduce the number of water closets required in men’s rooms, but only up to a point. Under the 2021 IBC, urinals can replace up to 67 percent of the required male water closets in a toilet room. A building needing 6 male water closets can meet that with 4 urinals and 2 water closets, but not fewer than 2 water closets. Urinals never count toward the female fixture requirement.

OSHA reads the other direction. Its two-thirds rule caps urinal substitution at roughly one-third, because water closets themselves can’t fall below two-thirds of the table minimum. For employer-only facilities, the stricter OSHA limit controls.⁴

All-Gender Restrooms

Amendments added to the International Plumbing Code in 2018 and expanded in 2021 let fixtures in single-user toilet rooms count toward the building’s required total, regardless of how the room is labeled, as long as the room is identified as open to all persons regardless of sex.⁵

Multi-user all-gender restrooms change the math. Instead of splitting the occupant load in half and running two calculations, you apply a single set of ratios against 100 percent of the total occupant load. In a 200-person building, the standard approach calculates for 100 males and 100 females; the all-gender approach calculates against all 200 using one set of ratios. Total fixture counts usually come out similar, but the layout options widen considerably.⁵

Does the ADA Add More Toilets?

No. The ADA Standards don’t increase the required fixture count. They dictate which of the fixtures you’re already required to provide must be built to accessible dimensions. You won’t add toilets because of the ADA, but you will need to build some of them differently.⁶

At least one stall in each multi-user restroom must be wheelchair accessible. When a restroom has six or more toilet compartments (or a combined total of six or more toilets and urinals), an ambulatory accessible stall is required on top of the wheelchair-accessible one. That six-fixture threshold is the count trigger most designers watch for.⁷

Penalties for Getting It Wrong

Undercounting fixtures creates exposure on two fronts.

On the workplace safety side, failing to provide adequate employee restrooms violates federal law. As of 2025, OSHA can assess penalties up to $16,550 for a serious violation and up to $165,514 for a willful or repeated one. The amounts adjust annually for inflation, and OSHA weighs employer size, history, and good-faith compliance when setting the actual figure.⁸

On the accessibility side, public-facing buildings with non-compliant restrooms face civil suits. Any individual who encounters non-compliant facilities can sue for injunctive relief, and courts can award attorney’s fees to the prevailing party. Fee awards often exceed the cost of the renovations themselves. When the U.S. Attorney General brings suit for a pattern of violations, the court can add civil penalties and monetary damages for affected individuals.⁹

Getting the count right at the design stage costs far less than fixing it after a complaint, and it starts with two numbers: your occupant load and the ratio for your occupancy classification.

1
International Code Council. 2021 International Building Code – Chapter 29 Plumbing Systems
2
International Code Council. 2018 International Building Code – Chapter 10 Means of Egress
3
International Code Council. 2015 International Plumbing Code – Section 403.1 Minimum Number of Fixtures
4
eCFR. 29 CFR 1910.141 Sanitation
5
International Code Council. International Plumbing Code: Providing Options for Designers of Modern Public Restrooms
6
U.S. Access Board. Chapter 6: Toilet Rooms
7
ADA.gov. 2010 ADA Standards for Accessible Design
8
Occupational Safety and Health Administration. 2025 Annual Adjustments to OSHA Civil Penalties
9
ADA.gov. Americans with Disabilities Act Title III Regulations