Stone was born in Scottsdale, Arizona. Stone's parents are Krista (née Yeager), a homemaker, and Jeff Stone, a contractor. Stone's paternal grandfather was of Swedish descent, and his family's surname was anglicized to "Stone" when immigrating to the U.S. through Ellis Island; some of her ancestors also lived in Pennsylvania Dutch Country.
Stone attended Xavier College Preparatory, an all-girl Catholic high school, as a freshman for one semester. She convinced her parents to let her move to California for an acting career and in January 2004, moved with her mother to a Los Angeles apartment, at the age of 15. She was then home schooled, so that she could audition during the day.
