In today’s world, length doesn’t matter
How long or short your fiction happens to be doesn’t matter in today’s world. No one’s chopping down forests of trees for your Kindle ebooks, after all. KENPC may or may not matter to you, again, depending on the genre in which you write.
That said, readers have expectations. So let’s say that you’re writing in a genre which is new to you. How do you know how many words to write?