16 pixels For Body Copy. Anything Less Is A Costly Mistake
I agree completely with this article.  As I've gotten older (now 43) I have had more and more trouble reading web sites.  In fact, I've noticed lately that I don't even try on some sites that have "small" fonts, I just close the tab.  There are some sites that I really like and I generally depend on my browser to help me out.  Chrome has a good habit of remembering my page zoom on a particular site so I don't even notice the font problem on subsequent visits.