This is a good question and not one that’s easily answered. The fact is that there are many definitions of what makes a story short. Perhaps the most widely known comes from Edgar Allan Poe, who said a short story should be of a length that can be read in one sitting. Translating that into word count is a bit difficult, but here’s what I’ve gathered from my own reading and writing experience. Generally short stories tend to fall under 15,000 words, with many in the range of 4,000-7,000 words. These numbers are not absolutes. Short stories have come in at a whopping 20,000 words and under a slim 1,000 words. (Anything under 1,000 words is often referred to as a short-short or flash fiction).
Perhaps a more useful way to think of the short story is in terms of scope rather than length. A novel might cover an entire family’s slow crumbling, such as Joyce Carol Oates’ We Were the Mulvaneys, where the family members’ individual reactions to a violence against the daughter causes a rift that can’t be mended. A short story, on the other hand, would cover just one facet of a larger conflict. This happens in John Updike’s “Gesturing,” which follows a married couple as they begin to settle into their separation. A more narrow scope, focusing on one main aim. is going to produce a shorter work of fiction.And that’s where your attention might be most productive: finding the focus in your short story and using only the words that are absolutely necessary to convey it in full.