Throughout her early career, Watson, 20, had been given a small weekly allowance of about $75, having no idea of the fortune she was amassing from the hit movie series until she had a "money conversation" with her father, Chris Watson, when she was around 17, the actress – and Brown University student in Rhode Island – tells December's edition of British Vogue.
Watson is now said to be worth $32 million, give or take a few pounds sterling.
"By the third or fourth film, the money was starting to get serious," she told Vogue, according to published reports in the U.K. "I had no idea. I felt sick, very emotional."
Harry Potter and the Deathly Hallows, Part I opens Nov. 19.