After moving from Nebraska to Pasadena, California, Penny is a young aspiring actor at the start of The Big Bang Theory, but viewers may wonder exactly how old she is on the show then and throughout its 12 seasons. Street smart and not as socially awkward as her nerdy neighbors, Penny (whose full name might be Penny Teller) is often regarded as attractive and patient, despite Sheldon Cooper’s insensitive mockery of her character. She begins her life in California as a server at The Cheesecake Factory while attempting to jumpstart an acting career. These traits make it easy to determine her age at the beginning of the series.

The Big Bang Theory ran on CBS from 2007 to 2019, highlighting the comical and social interactions between a group of CalTech physicists and their female counterparts. Over the course of the show’s 12 seasons, Penny slowly transitions from wanting to be an actor to having a promising career as a pharmaceutical sales representative. She also develops a growing sense of self and concentrates on her relationship with Leonard Hofstadter.

How Old Is Penny At The Beginning Of Big Bang Theory?

When the series begins, The Big Bang Theory takes place in the year it was filmed, 2007. In The Big Bang Theory season 1, episode 1, “Pilot,” Penny divulges that she is a Sagittarius and confirms with Sheldon in season 2 that she did not graduate from a community college in her hometown. Later on, the show clarifies that her birthday is December 2. That means that Penny is 21 years old at the start of The Big Bang Theory, making her the youngest of all the characters on the hit sitcom.

How Old Is Penny At The End Of Big Bang Theory?

After a long road that saw their relationship go from will-they-or-won’t-they to wedding bells, Penny and Leonard form a bond that solidifies everything Leonard desired when The Big Bang Theory began. A courtship that started when Penny moved across the hall from Leonard and Sheldon, Penny’s relationship with Leonard helped to define a marriage of equals. Since she was born on December 2, 1985, Penny is 33 years old by the time the series ends, just as she reveals her pregnancy in the Big Bang Theory series finale.

Given that Penny’s actor, Kaley Cuoco, was also in her 30s when The Big Bang Theory filmed the last season, it’s reasonable to believe that the showrunners mirrored Penny’s age to that of Cuoco’s. Both are Sagittarius, and both dated their onscreen counterparts in real life, although Cuoco and Galecki have since parted ways romantically. Appropriately enough, similar to the character she portrayed for 12 seasons, The Big Bang Theory star Kaley Cuoco was also 33 years old as the series aired its final episode on May 16, 2019.