It is important to follow a few guidelines when it comes to the length of your story if your desire is to get it published. If it's too short or too long, most agents will simply say "NO" and toss it, unless you are the rare exception to the rule (which almost never happens).
Generally
Novel over 40,000
Novella 17,500 - 40,000
Novelette 7,500 - 17,500
Short Story under 7,500
Flash Fiction [Sudden Fiction] 1,000
Micro Fiction & Micro Narrative below 300
Drabble 100
Nano Fiction 55
Twitter Fiction [aka twitterature] 140 characters or 23 words
To break this down a little more;
Commercial & Literary Adult Novels
80,000 - 89,999 Great
90,000 - 99,999 Generally Safe
Below 70,000 is considered too short
Above 110,000 is considered too long
SciFi & Fantasy
Least 60,000
Usual 100,000 - 115,000
Max 120,000
Mystery
60,000 - 80,000
Romance
60,000
Thriller
100,000
Westerns
50,000 - 65,000
Max 80,000
Memoir [Biography/Autobiography]
Least 70,000 - 79,000
Usual 80,000 - 89,999
Max 99,999
More serious subject matter can take up to 200,000 but the author must justify it
Humor & Gift
70,000 or less
Picture Books
500 - 600 [standard 32 pages]
Childrens
Least in both cases 16,000
5-8 yrs Middle Grade 20,000 [max 55,000]
8-12 yrs Upper Middle Grade 40,000 [max 55,000]
Young Adult
Least 47,000
Usual 55,000 - 69,999
Max 80,000 - 100,000
Chapters
There really is no set number of words per chapter. It is left up to the writer to determine what feels right for their story. Many writers try to stick to 1,500 - 3,000 words per chapter, others 10,000 - 15,000, and others have no chapters at all.
Several writers will try to average 15-25 chapters per 70,000 words. This is just a guideline if you wish to use chapters and remember this is all based on published authors.
Synopsis
500-800 words to describe your story [max 1,000]
YOU ARE READING
Resources to Better Writing (ReOrganizing & Editing)
Non-FictionI have done a considerable amount of research over the years in order to improve my writing abilities. Decided it might be a good time to share them with all the writers on Wattpad. I hope it helps. Enjoy!
