The number of restrooms in a building, structure, group of buildings, or other built object is the total quantity of distinct spaces holding toilets and related facilities. Individual toilet stalls are not counted as separate rooms. Adjoining men's, women's, unisex, or disabled-usage restrooms are counted as separate rooms.

Restrooms may or may not contain urinals, sinks, bathtubs, showers, bidets, jacuzzis, saunas, baby changing tables, or other such furniture or appliances. A single toilet or urinal is sufficient to make a restroom as long as toilet facilities form the predominant intended usage for that room.

What counts as a room is set by the source. Some registers count a kitchen and some do not, bathrooms are usually excluded from a room count and always excluded from a bedroom count, and hallways never count.

Because of that, a room count from a real estate listing and one from a building register are rarely the same number for the same building, and neither is wrong.