Blanche is described in the play as "about" five years older than Stella, who is "about" twenty-five. This would make Blanche thirty or older. Later, she admits to Stella that she has lied about her age to Mitch. For Blanche's birthday celebration, Stella only says she stopped at twenty-five candles on her cake. At the strained event, Blanche tries to keep up the illusion that she is under thirty.

Blanche's aging is an ongoing theme: she tries hard to arrange events so that she is only seen under soft lights and looks as innocent as possible. Part of this reflects the harsh social stereotyping of women over thirty, which assumes they must be used up and sexually experienced. Blanche is desperate to marry, so she does everything she can to look like a younger woman.

However, the lying about her age is also another symbol of Blanche's desire to live in a world of illusion. Her existence is a web of desperate but also romantic lies that she uses to shield herself from a reality that is too harsh for her to bear. She symbolizes the artist, arranging the world to look more beautiful than it really is.