Average length of books

General Fiction
 

Flash Fiction: 300–1500 words

Short Story: 1500–30,000 words

Novellas: 30,000–50,000 words

Novels: 50,000–110,000 words

Fiction Genres

Mainstream Romance: 70,000–100,000 words

Sub-genre Romance: 40,000–100,000 words

Science Fiction / Fantasy: 90,000–120,000 (and sometimes 150,000) words

Historical Fiction: 80,000–100,000

Thrillers / Horror / Mysteries / Crime: 70,000–90,000 words

Young Adult: 50,000–80,000

Children’s Books

Picture Books: 300–800 words

Early Readers: 200–3500 words

Chapter Books: 4000–10,000 words

Middle Grade: 25,000–40,000 words

Non-Fiction
 

Standard non-fiction (Business, Political Science, Psychology, History, etc.): 70,000–80,000 words

Memoir: 80,000–100,000 words

Biography: 80,000–200,000 words

How-to / Self-Help: 40,000–50,000 words

Original on ProWritingAid