Case Study — Typographic Design Patterns And Current Practices | Smashing Magazine

From a Smashing article. Very INTERESTING numbers here about RWD Fonts.

SOME NUMBERS ON THE IMPLEMENTATION OF RESPONSIVE DESIGN

42% of websites implement responsive design changes, including for layout, image scale, content and font size.

At a display width of 500 pixels:

  • Average line height: 28 pixels
  • Average font size of body: 15 pixels
  • Average number of characters per line: 77

At a display width of 700 pixels:

  • Average font size of headlines: 36 pixels
  • Average font size of body: 15.6 pixels
  • Average number of characters per line: 82.7

At a display width of 950 pixels:

  • Average font size of headlines: 37.9 pixels
  • Average font size of body: 16.1 pixels
  • Average number of characters per line: 84.8

At a display width of 1600 pixels:

  • Average font size of headlines: 40.7 pixels
  • Average font size of body: 16.2 pixels
  • Average number of characters per line: 86.8