Different Font Sizes

Sidebar to On Scalable Text.

Relative fonts
with styles

This font not specified.

This font is 100%

This test is 1em

This font is 2ex

This font is larger

This font is smaller

Absolute fonts
with styles

This font not specified.

This font is 12pt

This font is 20px

This font is 20

This font is 0.15in

This font is 0.4cm

This font is 4mm

This font is 1pc

Font settings
in HTML

This font not specified.

This font is small

This font is big

This font is +1

This font is 1

This font is -1

Discussion

IE 5.5 for Windows

In IE 5.5 for Windows, all of the font above looks approximately the same size with Font Size set to medium. With Font Size set to Smallest:

Not specified, 100%, and larger is smaller and readable.
1em, 2ex, and smaller is extremely small and barely readable.
The rest (12pt, 20px, 20, 0.15in, 0.4cm, 4mm, 1pc) do not change size.

Converting from one unit to another

If you are converting from one unit to another, the table at the top can help you see equivalents. When I changed the Optavia site from em to %, some the the equivalents were:

font-size (%)	font-size (em)	Selector
165%	1.7em	h1
125%	1.3em, 1.1em	h2
87%	0.85em	body
175%	1.8em	quote
100%	1em	[top list]

For more information (from W3C)

Font size in CSS2
Font style elelements in HTML 4.01 are deprecated in favour of style sheets

More font sizes in styles

[column repeated from
above for comparison]

This font not specified.

This font is 100%

This test is 1em

This font is 2ex

This font is larger

This font is smaller

This font is xx-small

This font is x-small

This font is small

This font is medium

This font is large

This font is x-large

This font is xx-large

Different Font Sizes

Relative fonts with styles

Absolute fonts with styles

Font settings in HTML

Discussion

IE 5.5 for Windows

Converting from one unit to another

For more information (from W3C)

More font sizes in styles

Relative fonts
with styles

Absolute fonts
with styles

Font settings
in HTML