This really depends on the purpose of the page. Consider the following:
- Are you writing a page that you want Google to index and potentially show when people search for whatever the page is about?
- If the page is within a competitive market do you want it to show for long tail keywords?
- Are you writing a page for your audience so don’t need the page to show in search engines?
- Do you want the page to contribute to the ranking of your website?
- Is it hosted on your own site or will it contain links to sites you want to rank?
A quick bit of research shows that really short webpages are indexed by Google and can show in Google searches. For instance I found a page on twitter that contains a single tweet. The page had 90 words altogether including the text in menus and the footer. So if your purpose is to be indexed by Google then as low as 90 words can suffice.
If, however you are in a competitive industry or you aren’t going to be doing much to market the article then you may want a longer article in the hope of showing for long tail searches.
If you are writing for your audience such as regular visitors to your blog then there is no minimum number of words. Posts under 500 words tend to be more popular as people often don’t have enough of an attention span to get through longer posts when they are browsing the internet.