The study, published in the journal Science, calculates the amount of data stored in the world by 2007 as 295 exabytes.
That is the equivalent of 1.2 billion average hard drives.
The researchers calculated the figure by estimating the amount of data held on 60 technologies from PCs and and DVDs to paper adverts and books.
'If we were to take all that information and store it in books, we could cover the entire area of the US or China in 13 layers of books,' Dr Martin Hilbert of the University of Southern California told the BBC's Science in Action.
By 2007, 94% of stored information was kept digitally
Computer storage has traditionally been measured in kilobytes, then megabytes, and now usually gigabytes. After that comes terabytes, petabytes, then exabytes. One exabyte is a billion gigabytes."