Fifty Shades of Grey, the e-book erotica that has become the hottest publishing phenomenon of the year, is now the bestselling book ever in Australia. That's according to Nielsen BookScan, which since 2003 has surveyed more than 1000 retailers to produce its bestseller lists.

E. L. James's spankbuster has sold more than 1.28 million copies in print and e-book editions and has been top of the national bestseller lists for 16 consecutive weeks. The previous bestseller was J. K. Rowling's Harry Potter and the Deathly Hallows.

But James's sales pale when compared with her home market of Britain where the print edition of Fifty Shades of Grey has sold more than 3.8 million copies. When e-book sales are added, its sales top 5.3 million.

The second and third instalments in her saucy saga, Fifty Shades Darker and Fifty Shades Freed, have sold 779,000 and 705,000 respectively in Australia; in Britain they have sold more than 2 million each.

The success of the Fifty Shades trilogy has spawned a burst of erotica from other publishers. Bared to You by Sylvia Day and Destined to Play by Indigo Bloome have recently surged into the national top 10.

Jason Steger is literary editor at The Age