What is the smallest size a full bathroom will fit?

The smallest size a full bathroom will fit is generally considered to be around 20 square feet (2 square meters). This allows for a toilet, sink, and a 36-inch (91 cm) shower or bathtub. To make the most of a small space, one can use wall-mounted fixtures, such as the toilet and sink, and a corner shower or bathtub. If space allows, adding a storage cabinet and a towel rack can also be helpful.