There is no ‘best font size’. Just don’t ‘fix’ your font size absolutely.
You may be aware that the same font, at the same point size on a Macintosh “looks smaller” than on most Windows machines. In a nutshell, this is because the “logical resolution” of a Macintosh is 72dpi, while the Windows default is 96dpi. The implications of this are significant. Firstly, it guarantees that it is essentially impossible to have text look identical on Macintoshes and Windows based systems. But if you embrace the adaptability philosophy it doesn’t matter.
What? If you are concerned about exactly how a web page appears this is a sign that you are still aren’t thinking about adaptive pages. One of the most significant accessibility issues is font size. Small fonts are more difficult to read. For those of us with good eyesight, it can come as a shock that a significant percentage of the population has trouble reading anything below 14 point times on paper. Screens are less readable than paper, because of their lower resolution.
Does that mean the minimum point size we should use is 14 pts? That doesn’t help those whose sight is even less strong. So what is the minimum point size we should use? None. Don’t use points. This allows readers to choose the font size which suits them. The same goes even for pixels. Because of logical resolution differences, a pixel on one platform is not a pixel on another. You can still suggest larger font sizes for headings and other elements. CSS provides several ways of suggesting the size of text in such a way as to aid adaptability. A LIST APART
UK Government recommendations on best fonts to use:
Use only clear, commonly used fonts. Avoid the use of small text. Users should have the ability to scale fonts.
Guidelines for UK Government websites
Illustrated handbook for Web management teams
Jakob Nielsen’s Readability Guidelines for Website Font Size
- Do not use absolute font sizes in your style sheets. Code font sizes in relative terms, typically using percentages such as 120% for big text and 90% for small text.
- Make your default font size reasonably big (at least 10 point) so that very few users have to resort to manual overrides.
- If your site targets senior citizens, use bigger default font sizes (at least 12 point).
- If possible, avoid text that’s embedded within a graphic, since style sheets and font size buttons don’t have any effect on graphics. If you must use pictures of text, make sure the font size is especially large (at least 12 point) and that you use high-contrast colors.
- Consider adding a button that loads an alternate style sheet with really big font sizes if most of your site’s visitors are senior citizens or low-vision users. Few users know how to find or use the built-in font size feature in current browsers, and adding such a button within your pages will help users easily increase text size. However, because every extra feature takes away from the rest of the page, I don’t recommend such a button for mainstream websites.
- Maximize the colour contrast between the text and the background (and do not use busy or watermarked background patterns). Despite the fact that low-contrast text further reduces readability, the Web is plagued by gray text these days.’
Jakob Nielsen’s Alertbox, August 19, 2002
Jakob Nielsen’s Top Ten Web Design Mistakes of 2005
- #1 – Legibility Problems
Bad fonts won the vote by a landslide, getting almost twice as many votes as the #2 mistake. About two-thirds of the voters complained about small font sizes or frozen font sizes; about one-third complained about low contrast between text and background.
Jakob Nielsen’s Alertbox, October 3, 2005: