Dionne, played by actress Brittany Murphy in the 1995 film Clueless, was a supporting high school senior whose exact on-screen age is rarely stated explicitly in dialogue.
Because the film does not provide a direct birth date for the character, her age must be inferred from production details and casting norms at the time.
Below is a verified breakdown of how old Dionne was during production and how the film situates her within the story timeline.