In the movie Grease she is portrayed by Jamie Donnelly.
Jan is a plump young woman with an average height, a slightly peach skin tone, black pigtails and baby bangs. Her first outfit was seen in the first scene of the movie with the Pink Ladies; it was a blue blazer with ruffles in the middle, her Pink ladies jacket, and a long yellow checkered skirt with matching sneakers.
Funny, loud, and awkward member of the Pink Ladies. Loud and pushy around girls, but sweet around boys. She likes to eat, and is the nicest girl of the Pink Ladies, though she could be a bit mean if needed - like glaring at Patty Simcox when she sat in Jan's place. She eats leftovers, and is generally friendly and upbeat.