The short, unhelpful answer is: stop when it feels right.
That means relying on your story instincts. Don't rush things, don't drag things. When the story's complete, end it. If it's not yet been told, don't end it. But don't kid yourself into thinking it's not over yet either and writing onward just because you don't want it to end. And don't jump the gun and end it too soon either.
Goldilocks.
More concrete advice would just be to write the story, and worry about where to end it later. You can always trim off. But there has to be something to trim first.
I don't fangirl. I fandragon.
Have you thanked a teacher lately? You should. Their bladder control alone is legend.
^ Seconding Rach above me. You really have to look at the pace of your story, but, in the end, a story is finished when a story is finished and there is no right answer.
A writer is a world trapped in a person— Victor Hugo
Ink is blood. Paper is bandages. The wounded press books to their heart to know they're not alone.
