There is no one definitive answer to this question. In general, blog posts should be between 500 and 1,000 words long.
However, the length of a blog post will vary depending on the topic, the tone of the article, and the audience that it is aimed at.
Ultimately, it is up to the author to decide how much content they feel is necessary for a given post. However, taking into consideration the audience that the blog is aimed at, as well as the tone of the article, 500 words should be a pretty good guideline.