Kate Winslet was born on October 5, 1975, in Reading, Berkshire, England, to Sally Anne (née Bridges) and Roger John Winslet. Her mother worked as a nanny and waitress, and her father, a struggling actor, took labouring jobs to support the family. Her maternal grandparents were both actors and ran the Reading Repertory Theatre Company. Winslet has two sisters, Anna and Beth, both of whom are actresses, and a younger brother, Joss.
The family had limited financial means; they lived on free meal benefits and were supported by a charity named the Actor's Charitable Trust. When Winslet was 10, her father severely injured his foot in a boating accident and found it harder to work, leading to more financial hardships for the family. Winslet has said that her parents always made them feel cared for and that they were a supportive family.