Sarah Lee Bolger was born on February 28, 1991 in in the town of Dublin in the Republic of Ireland. She is the daughter of Monica, a former banker, and Derek Bolger, who is a butcher and owns an organic meat shop in the suburb of Rialto called "Ennis Butchers". Her younger sister is fellow actress Emma Bolger. As a child, Sarah attended Dublin's The Young People's Theatre School, which led to her first on-screen role at age six in the 1999 television movie A Love Divided alongside Orla Brady and Liam Cunningham. From 2003 to 2009, she attended Loreto High School in Rathfarnham. Having missed mock exams due to her work schedule, Sarah substituted attending school with on-set tutors with a total of nine subjects, English, Maths, Irish, Biology, Business studies, French, Classics, and Geography, that she studied for towards her June 2009 Leaving Certificate. Outside of acting, Sarah has expressed interest in computers and writing and keeps fit by going to the gym and walking her dogs.