Opinions differ from person to person online about how long and informative and good article should fare. Some people who read online say 200 words are enough; whereas some say there an article should contain at least 700 words to generate a good traffic.
The one thing we should remember is that the article should be tailor made to fit the requirements of the reader or the audience. The size of the article should not be too short or too long for the information you wish to share. The technique to guess the right size of the article is usually determined by the quality of the content contained in the article. The better the article the shorter it is but it should encapsulate all the knowledge and information the readers seek to read online.
The purpose of the article really matters about how long it should be. 250 word articles or less are enough to generate back links when they are submitted to article directories. Articles should be tailored to be of a particular size depending on its readers and purpose of the article.
Atleast, articles should be of 250 words or in excess if the purpose of the article is to generate traffic as needed. 300 to 550 word articles are of good length if the aim is to target and get picked up by content search by webmasters. A 400 word good article will be enough and satisfactory for their needs. An article which is too long may bore the reader and the writing should be to the point and short as possible but it should pack all the information in a succinct way.
An article with valuable information to catch the eyes of readers and to generate traffic to your website can be of the size of 300 to 400 words. It depends upon how you want to appear to the reader. That is to portray you know what you are writing about and also that there are limits to the information and knowledge you can provide.
Making the readers to stay with your website and read what you write is your niche. An article of say perhaps 350 words will be sufficiently effective and long enough to be informative and keep the reader to seek your writing for additional information because they will tend to feel you are the expert in what you write about.