Well, it's hard to give an exact figure because it depends on a lot of things. Generally, though, an average 300-page novel might have anywhere from 80,000 to 120,000 words. Different genres and authors can have quite different word counts per page.
The word count of an average 300-page novel is not fixed. It usually ranges from 90,000 to 110,000 words. This can change based on how dense the writing is and the formatting of the pages.