Google’s general philosophy surrounding AdSense ad placement is to make them blend with the rest of a site’s content, so it’s always struck me as a little strange that publishers have had no control over the fonts displayed.
That’s just changed, with Google announcing an update which allow ads to be rendered in a number of fonts. Don’t get too excited, though, because there’s a small selection — Arial, Times and Verdana.
You don’t get much control beyond that. Obviously, you can’t alter the size of the fonts because the ad blocks are specific sizes and you’d end up clipping ads (this often happens if a user manually increases the font size on their browser). It only works on ads displaying Latin-based characters, and it won’t affect image-based adverts.
The default is to use the “Standard AdSense font family” so you don’t have to worry that all your ads will suddenly transform into Times font if you don’t want them to. It will be interesting to see if this change makes any difference to conversion rates. Never an exact science, of course.