The Hollywood Reporter set out to determine the biggest box office BOMB of ALL TIME . . . and they considered notorious over-priced movies like “Cleopatra” from 1963 and flops like “Heaven’s Gate” from 1980.

Ultimately, they decided it was Disney’s 2012 movie John Carter, which cost $263.7 million to make, plus at least $100 million more for marketing.  But it only earned $284 million worldwide . . . HALF what it would’ve needed to break even.

That’s worse than “Cutthroat Island” in 1995, which reportedly cost $98 million . . . and up to $115 million when domestic marketing costs are factored in.  And yet, the movie only earned $15.7 million WORLDWIDE.