How long are short stories?
Short stories can be as short as you please. Back in the days when I wrote for magazines, I’d sell the occasional “flash” fiction story. They were always shorter than a thousand words.
If you’re selling short stories on Amazon, I suggest that that your ebooks contain over 5,000 words. If you’re writing flash fiction, compile two or three or more stories. This is a suggestion – you can write at whatever length you choose.