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Re: Browser font sizes

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From: Terence de Giere
Date: Mar 6, 2002 8:27PM

Mr. Wilson --

I do not have any statistics on font size changes by users. In some
usability testing in 2000 where I specifically asked the questions of a
number of disabled users working from home (whose vision was typically
normal) only one of 25 sighted subjects had set the font size on their
browser to a larger size to be able to read text. I have occasionally
observed others who enlarged the font size, not always because they
could not read a page with "normal" sizes, they just liked big fonts.

Another issue that affects font size is monitor resolution, or rather
the operating system setting for resolution in dots per inch (dpi) or
dots per centimeter. This affects the ratio of the size of images to
font size and hence to line length etc., in relation to images. Some
newer browsers, such as IE for the Mac, and Netscape 6 have settings to
adjust for this, providing greater cross platform consistency, but older
browsers do not. The Mac displays at 72 dots per inch, and most Windows
systems typically display at 96 dots per inch, and a small number of
users have Windows systems set at 120 dots per inch. Assuming that at
any resolution setting, a ruler in an application such as Microsoft Word
displays life size, as the resolution increases, more pixels are used to
create the font printing to the screen, but the images will become
proportionately smaller in relation to the font size. An image on a Mac
that is 5 centimeters wide on a Mac will display 3.75 centimeters wide
on a Windows machine at 96 dpi and 3 centimeters wide on a Windows
machine set to 120 dpi, assuming the effect is not adjusted for in one
of the newer browsers. Visually this effect is usually experienced as
the fonts getting larger if the same monitor size is used for
comparison. If one sets the system to a higher resolution, it would be
necessary to reduce the size of the image on the monitor to in order to
get the image to display, physically, at the correct dpi. Typically the
higher resolution settings for Windows would be used with a large
monitor. There are experimental monitors being developed that have
resolutions as high as 300 dpi.

Most users do not change browser defaults. As with setting font sizes
larger, the dpi resolutions settings probably do not have any useful
statistics, unless a company like Statmarket (very expensive) tabulates
that information. The only statistics on monitor resolution I have seen
is the pixel size of the screen, not the dpi figure. I have however
noticed that at least as many people have their machines set to 120 dpi
on Windows as have set the font sizes larger using browser settings.
This higher dpi can greatly affect the appearance of Web page on some
browsers, and can break apart many carefully crafted visual designs.

Older users are likely to need some enlargement of fonts due to
deteriorating vision. The font sizes on many Web pages today are too
small for such users. Whether they know how to enlarge the font is a
good question, since so many people do not know it can be done.

The variation of fonts sizes in browsers also appears to be greater when
relative sizing in Web pages is used. Especially the difference between
the newest graphical browsers and Netscape 4 browsers. This may be one
reason why many designers prefer to use absolute sizing, which is less
accessibility friendly than relative sizing.

Of course, users of special low vision browsers will probably see the
page with a completely different font and size than a designer would
expect. Any one interested in seeing how font substitution and resizing
can affect a visual design should look at their pages on WebTV, where
the WebTV system determines all fonts and mostly their display size.
Because of the low resolution of TV, the font sizes are increased quite
a bit for legibility, and only a sans serif font is used. Text on
graphics is often unreadable on WebTV.

Terence de Giere
<EMAIL REMOVED>



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