Via Forbes

To compile our list we used information gathered for the Celebrity 100 to look at the last three non animation movies each actor starred in over that last three years. We added each actor’s upfront and backend pay on all three movies to come up with a total compensation number. We then added up the operating income of the three movies to come up with a total operating income number and
then divided total operating income by total compensation. Each return on investment number represents how much the studio is paid for every dollar invested in the star.

No. 1 Kristen Stewart

For every $1 Stewart is paid, her films earn an average $55.83. Stewart tops our list thanks to her paydays for two Twilight movies:
New Moon and Eclipse. She ranks higher than her costar Robert Pattinson (even though they earn the same amount on the films) because he has branched out more so only one of his Twilight films is eligible for this list.

No. 3 Robert Pattinson

For every $1 Pattin son is paid, his films earn an average $39.43. The Twilight star ranks lower than Kristen Stewart because he’s been busy. Only one of his Twilight films, Eclipse, qualifies for the list. The other films we looked at for Pattinson were Water for Elephants and Remember Me.

Read more on who else made the list here