It's an accepted fact that most Web surfers never change the defaults in their browser. In particular, that means the default "text size," which Internet Explorer (the most common browser) refers to as "medium." and Firefox refers to as "Normal." Fortunately, both place it under the "View" menu.
- What is the text size set to in your browser?
- Have you looked at your Web site with the text size set to medium/Normal?
You should ask your Web designer or Webmaster to show you how your site looks (with default settings) in Internet Explorer on a Windows computer, Safari on a Macintosh, and Firefox under Windows. That's what your visitors are seeing. You might also ask what percentage of your visitors fall into each category.
By the way, Macintosh computers assume displays have 72 pixels per inch (which is nice for typography, since 1 pixel = 1 typesetter's point measure). Windows computers assume 96 pixels per inch. This means that a poorly executed site design can result in tiny text on Windows systems (but looks fine on your designer's Macintosh).
Most visitors won't fight to read your site. The Back button is just too close at hand.