By Jamie Appleseed, Aug 31, 2010

I see the mistake again and again – web designers that either don’t adjust the width of their form fields at all or adjust it based on what looks best in the layout of the page. To achieve good usability you should however adjust the width of your form fields so it matches the length of the expected input.

Read full article: http://www.baymard.com/blog/form-field-usability-matching-user-expectations