Which Harry Potter book by J.K. Rowling is the longest in the original UK edition?

Harry Potter and the Order of the Phoenix is the longest book in the original UK Harry Potter series by page count.

The UK hardback edition contains 766 pages, making it longer than the other six novels in their original British editions. The story follows Harry’s fifth year at Hogwarts and introduces the secret student group known as Dumbledore’s Army.

Page totals vary by format, edition, typography, and country. The American hardcover edition has a different page count, so claims about the “longest” book should specify the edition or measure being used. Word counts can also differ from page counts.

The novel was published in 2003 and is notable for the Ministry of Magic’s growing interference at Hogwarts, Dolores Umbridge’s appointment as High Inquisitor and headmistress, and Harry’s visions connected to Voldemort.