What's the perfect point size for body text in printed documents and in web design?

The creativity there has no rules, on the web you can do what you need by choosing your sizes, but you should care that you deliver your message from the sizes you choose, the sizes can tell how much this words is important and the same for print as i think.

so try to test it before you publish it. this is the rule take you to success with anything.

Font Size should based on Line Hight and container width so user won't feel any destruction during reading , Normally for Web14px is standard font size.

 

Chris Pearson write a excellent article regarding Golden Ratio of Typography its must read item http://www.pearsonified.com/2011/12/golden-ratio-typography.php

In print, the op­ti­mal point size for body text is10–12 point. On the web, the op­ti­mal size is15–25 pixels. the point-size sys­tem is not ab­solute—dif­fer­ent fonts set at the same point size won’t nec­es­sar­i­ly ap­pear the same on the page. So you need to let your, eyes be the judge. Don’t just rely on the point size.

It depends on the font, but12 is the normal size.

Most Often10px to12px is best for printed documents and web design.

10 to11 points