to or not to specify font sizes

[gm1234]

Now this is really serious. There are some who say that a font size of 10 to 12 points would be good, some others who say that font sizes should be specified in percentage of 80 to 90% and some others who are against specifying font sizes. I wonder which one would be correct on the web usability point of view. Any help?

[Fang]

What the W3C say (http://www.w3.org/QA/Tips/font-size)
On a practical note absolute-size (xx-small etc.) are not consistent across browsers.
If you define a relative base font-size, some users who have inadvertently set their browser Text size to the smallest option will have a tiny text size.

[Robert Wellock]

Use relative units in CSS though whether you chose %, em or px is your choice but remember some buggy browsers have issues with those units.

[Stephen Philbin]

On the rare occasion I specify a font size I usually go with 0.7em. I prefer to give my users the maximum possible control.

I often increase the font size in my browser when reading other peoples [pages when I'm sat in my arm chair form farther away from the screen as usual. I'm sure people that have difficulty reading medium sized fonts from any distance from the screen would be even less appreciative of having their text size fixed than I am at having to lean foward (oh woe is me) to read the text.

[MstrBob]

I prefer to simply set my text at 1em. This gives it a gernal size, and since em is a relative unit, it allows the text to resize upon the users request. Plus, 1em is generally an easy-to-read font size, without being huge. 1em for me :D

[toicontien]

I have no problem specifying font sizes that might be too small for people to read, but I like to keep a note on my sites that you can incease the text size if so desired. I also believe the designer should know best what size text should be, but keep in mind that around 10 words per line on screen is about the max you want to go.

If you go below a text size of 10 points, keep the number of words per line to around seven. I never specify font sizes in anything but percentages and ems. Internet Explorer/Win won't let you resize text via the View menu if the font units are anything else but percentages, relative units, or ems. That's why Robert Wellock said "some buggy browsers have issues with those units."

[Webnauts]

Pixels... IE PC doesn't resize text. Example: body { font-size: 12px; }

Em... IE PC displays unreadable small text when user browser is set to smaller and em is less than 1. Example: body { font-size: 0.80em; }

Percentage usually works. Example: body { font-size: 80%; }

Keywords usually works. Example: body { font-size: smaller; }


Some resources about fonts and accessibility:

Care With Font Size: http://www.w3.org/2003/07/30-font-size

Font sizes: http://hotwired.lycos.com/webmonkey/99/41/index3a_page3.html?tw=design

Using relative font sizes: http://diveintoaccessibility.org/day_26_using_relative_font_sizes.html

Accessible web text - sizing up the issues: http://www.mcu.org.uk/articles/textsize.html

Font size: the 'font-size' and 'font-size-adjust' properties: http://www.w3.org/TR/REC-CSS2/fonts.html#font-size-props

What's wrong with the FONT element? http://www.mcsr.olemiss.edu/~mudws/font.html

Size matters: http://www.alistapart.com/stories/sizematters/

Making Text Legible: http://www.lighthouse.org/print_leg.htm

TYPOGRAPHY - Font Sizing: http://www.d.umn.edu/itss/support/Training/Online/webdesign/type.html#size


Some resources about fonts and usability:

A Comparison of Popular Online Fonts: Which is Best and When? http://psychology.wichita.edu/surl/usabilitynews/3S/font.htm

A Comparison of Popular Online Fonts: Which Size and Type is Best? http://psychology.wichita.edu/surl/usabilitynews/41/onlinetext.htm

Font size - Typical on the Internet: http://www.humanfactors.com/downloads/fontsize.asp

So, What Size and Type of Font Should I Use on My Website? http://psychology.wichita.edu/surl/usabilitynews/2S/font.htm

Determining the Best Online Font for Older Adults: http://psychology.wichita.edu/surl/usabilitynews/3W/fontSR.htm

Which Fonts Do Children Prefer to Read Online? http://psychology.wichita.edu/surl/usabilitynews/3W/fontJR.htm


Table of font sizes for your reference:

100% = 1.0em = 16px = 15pt
95% = 0.95em = 15px = 14pt
90% = 0.9em = 14px = 13pt
85% = 0.85em = 13px = 12pt
80% = 0.8em = 12px = 11pt
75% = 0.75em = 11px = 10pt
70% = 0.7em = 10px = 9pt
65% = 0.65em = 9px = 8pt

[Paul Jr]

I try to keep my font sizes lower rather than higher, because things don’t look as strange when you increase the font size as they do if you decrease it.

[BuezaWebDev]

I agree with Paul.

Small size fonts do tend to make a layout look professional.

[Webnauts]

I use myself Arial or Verdana with minimum 0.85em