Which book in J.K. Rowling’s Harry Potter series is the longest by word count?

Harry Potter and the Order of the Phoenix is the longest book in J.K. Rowling’s Harry Potter series by word count. The English edition contains about 257,000 words, making it substantially longer than the other six novels.

Published in 2003, the fifth book follows Harry’s return to Hogwarts during a period when the Ministry of Magic refuses to accept that Lord Voldemort has returned. Dolores Umbridge is installed as the school’s High Inquisitor and later as Headmistress, while Harry and his friends create Dumbledore’s Army.

The book is also the longest in the series by page count in many editions, although page totals vary with typography, paper size and language. This makes word count the more useful comparison. The film adaptation, released in 2007, necessarily omits many subplots and details from Rowling’s much longer original.