Forbes did the math and compared celebrity salaries to studio return on investment. In many cases it’s not the celebrities’ faults that their movies failed at the box office, although it may speak to their need to pick better films in the future – or ask for a salary that’s tied to box office take, which isn’t going to happen. First on the list is Nicole Kidman, but she also lands at the top of “quickest return to pre-baby weight” ranking, so maybe it balances out for her.

1. Nicole Kidman

Kidman has an Oscar and earns $15 million paydays, but she’s proved to offer a poor return on investment. Despite bringing in $370 million in worldwide box office, The Golden Compass only grossed $3.36 for every dollar Kidman was paid. The Invasion lost $2.68 for every dollar that went to Kidman. She has a chance for a high-profile comeback with this fall’s epic Australia, which could earn the Aussie her third best actress nomination.

For every dollar she was paid, Nicole Kidman’s movies averaged $1 of gross income.

2. Jennifer Garner

Garner has stayed fairly under the radar since her 2005 big-budget disaster Elektra, which cost $40 million to make and earned only $56 million worldwide. Unfortunately for Garner her follow-up films didn’t do much better. Both Catch and Release and The Kingdom underperformed at the box office.

For every dollar she was paid, Jennifer Garner’s movies averaged $3.60 of gross income.

3. Tom Cruise

His recent cameo as a foul-mouthed studio exec in Tropic Thunder is earning raves and might usher in the era of Tom Cruise comedies. In the meantime, Cruise has to deal with the fallout from his recent dramatic blunder, Lions for Lambs. The film’s box office ($63 million worldwide) was bad enough that even without taking any upfront pay Cruise still earned the movie only $1.88 for every dollar he was paid.

For every dollar he was paid, Tom Cruise’s movies averaged $4 of gross income.

4. Cameron Diaz

The highest paid actress in Hollywood, Diaz pulled in $50 million last year. But her high salary makes it hard for the romantic comedies she stars in to earn a good return. The Holiday brought in $205 million worldwide but Diaz’s high payday meant the film only grossed $3.70 for every dollar Diaz was paid.

For every dollar she was paid, Cameron Diaz’s movies averaged $4 of gross income.

5. Jennifer Lopez

The singer/actress/designer has struggled at the box office for the past few years, choosing small projects like 2006’s El Cantante, a low-budget musical biopic starring her husband Marc Anthony, which barely registered at the box office. Her last big film was 2005’s Monster-in-Law, which grossed $155 million worldwide returning $6.85 for every dollar Lopez was paid.

For every dollar she was paid, Jennifer Lopez’s movies averaged $4.10 of gross income.

[From Forbes.com via WeSmirch]

Rounding out the list are Jim Carrey at a $4.11 return, Nicolas Cage $4.16, Drew Barrymore $4.38, Will Ferrell $4.67, and Cate Blanchett at $4.97.

Forbes notes that actors who command less than $10 million a picture are usually a better return on investment except for poor Jennifer Garner. She had two big films, The Kingdom and Catch and Release, that pretty much tanked at the box office last year and dragged her down. Russell Crowe was named the most improved with a return of $6.88 per dollar. That’s mainly due to his hit American Gangster. It looks like one big blockbuster can make all the difference. Will Australia be the film that brings Kidman back in the black for her employers? We’ll have to see.