Which Harry Potter book did J.K. Rowling identify as the longest in the original seven-book series?

Harry Potter and the Order of the Phoenix is the longest book in J.K. Rowling’s original seven-book Harry Potter series.

The fifth novel was published in 2003. Its English editions are notably large, with the United Kingdom hardback running to 766 pages and the United States edition running to 870 pages. Page counts vary by format and edition, but the novel is generally recognized as the series’ longest.

The story follows Harry’s fifth year at Hogwarts and introduces the student resistance group Dumbledore’s Army. It also portrays the Ministry of Magic’s refusal to accept the return of Lord Voldemort and Dolores Umbridge’s appointment as Hogwarts High Inquisitor.

Readers sometimes assume Harry Potter and the Deathly Hallows is the longest because it is the concluding volume and contains many major events. In standard English editions, however, Order of the Phoenix has the greater page count.