Everybody loves extra space in their bathroom, but adding square footage isn't always an option. Here are several design principles and techniques you can use to provide an expansive feeling in a small space.
Use Soft Colors
Pale colors on the walls and floor tend to give the illusion of space. Avoid using strong colors except on accessories, towels and decorations.
Get rid of the shower curtain or frosted-glass shower doors and replace them with clear glass. It will open up the shower area, making it a part of the entire room and giving the appearance of more space.
Open Up Floor Space
If you have alternative storage or a linen closet, replace the vanity cabinet with a pedestal or wall-mount sink. While the additional floor space won't exactly be usable, it will trick the eye into believing the room is larger.
If the bathroom doesn't have natural light, try recessed lighting. It is unobtrusive and won't "bring the ceiling down" and make the room feel shorter, plus it can be placed anywhere and focused onto any task area.
If you can, install a bigger window; or at least open up the curtains. Use window treatments that can be partially opened, perhaps on top. Regular or tubular skylights are other great options to let the sun in.
To expand a small room, add to the ceiling. A light fixture with a ceiling medallion will draw the eye up, as will crown molding. Just make sure the molding is not too large for the space. Other architectural features like chair rail and wainscoting can also help visually expand a small space. (Source: Diynetwork)