KARACHI: Katy Perry’s behind-the-scene 3D documentary ‘Katy Perry- Part of Me’ has flopped at the US Box Office.

The film features Perry’s life from pre-fame days up to her ‘California Dreams’ World Tour, and her marriage split from English Comedian Russell Brand.

The film earned a gross of just $7.14 million over the weekend. A measly amount, compared to Justin Bieber’s ‘Never Say Never,’ which pulled in nearly $30 million on its opening weekend. With an expected turnaround of over $70 million, Bieber’s documentary has made it to the top in this genre.

According to industry sources, such films usually have a shelf-life of about five weeks. And at best, they drop by about 50 percent each week following the release at the box office. It is predicted Perry’s documentary is expected to earn just between $16 million and $19 million.