“The font size you choose will be applied to the body of the ad,
with the title scaled appropriately. In order to fit the ad text
correctly, the actual font size will vary for each format size, font
face, and user-specific settings such as browsers and operating
systems. In addition, some formats sizes currently have very limited
room, so the font size application will be most apparent in cases where
the number of ads appearing in your ad units varies automatically in
order to maximize your performance.
Your ads are currently set at the default size for AdSense, which is
the equivalent of ’small’. You can select a new font size on an
account-wide basis in the Ad Display Preference section of your My
Account tab, or on an individual ad unit basis for new and existing ad
units.
If you’re creating new ad units, you can choose between the AdSense
default font size, your new account-wide font size (if you’ve selected
one using the instructions above), or a separate size. To update
existing ad units you’ve created using the Manage Ads feature, visit
the ‘Manage Ads’ page under your AdSense Setup tab. Any font size
changes you make on an individual ad unit basis will be maintained even
if you change your account-wide default in the future.”
