First of all, it doesn’t always have to be long. Some will say that a post should be at least 500 words long because you want the reader to think that he or she is getting something for their time. While this is good advice, remember the most important issue – valuable content.
What if you just have a short update that you want to post and there is no way that you can get more than 300 words out of it? Should you wait until you have something more and then write a 500 word post? I’d say no. Look at one of the biggest marketing gurus out there, Seth Godin. Some of his blog posts are between 60-200 words. And his blog is huge!
If you do write a short blog post, just make sure that you are not wasting the reader’s time. They have offered you a sacrifice by believing that what you have to say is important enough that he or she should spend a few moments with it.
If you have an update to a previous piece, it may only be 300 words and that is okay. Never allow length to undermine the message. If a reader believes that you are more interested in posting a certain length than giving them valuable content, they will walk away. They will go somewhere else.
All that to say, try to keep your posts above 300 words, but this is not a hard and fast rule. Short posts should not be a normal length, but every once in a while, if you have an update or an important piece of advice that only warrants 300 words or less, it is okay to use this length (like Seth Godin does).