What is a 300×50?
This ad size is known as a Mobile Banner, or Smartphone Banner. It is the little brother of the 320×50, which is known as a Mobile Leaderboard.
A 300×50 ad unit is most commonly used as an ad on mobile phones. They often slide into view as an Anchor Ad on mobile sites, with the ability to close them by sliding back.
300x50s generally do not cost much, as they are so small.
What it looks like
This is how it looks:
300×50 Advice for Site Owners
A 300×50 isn’t a bad way to monetise mobile inventory on your site. However It is unlikely to be your largest revenue driver. This is because it is not a very large ad, and cannot contain very interesting messaging.
If you receive a good amount of visitors from smartphones it is worth experimenting with adding this ad size to your site. Give it a few months and see if it makes you any money – and compare that to any loss of visitors you may experience.
Note: To avoid annoying your users, it is generally advised to run these ads with a way to close them.
300×50 Advice for Ad Buyers
300x50s are one of the smallest ad sizes. They can be effective if used right, and often don’t cost that much to run. They are especially useful as they can hit users at a different point than usual desktop ads.
To get the most out of a 300×50, make sure you have a concise message to convey and simple clear graphics. This way you can get your message across in a tiny space.