Definition: Standard Ad Unit

The Online Advertising Guide recommends you use IAB standard ads, as it makes the whole ad buying/selling process much easier. Imagine if every website made random sized ads that only ran on their site – the cost of running a large online ad campaign would be astronomical as web designers would have to design ads to fit every site. To combat this problem, the online advertising industry has standardised ad sizes over the years so that advertisers and publishers don’t need to work so hard to run ad campaigns.

A standard ad is what you see on most pages on the internet now, and they come in three main sizes: 728×90, 300×250 and 160×600 (or sometimes the 300×600). These measurements are in pixels and are horizontal and then vertical – see below (or on this site) for example:


*Not to scale


These are the most profitable and widespread ads out there, so add them to your site to enter the online advertising world with the least effort and most reward.

WARNING: There used to be standard 5 standard ad units, but two of them were retired for being terrible. The other two were 468×60 and 120×600 – both of which look kind of tiny, and sell for much less money than the above three. Do not use these ad sizes in the hope of monetizing them well – they will let you down. (Please note however that sometimes a 468×60 is shown in a 728×90 slot or a 120×600 is shown in a 160×600 slot – do not panic about this, it’s just how it works).

For full details on all of the most prevalent ad sizes currently in use, please take a look at our convenient Ad Size Guide.

Note: The IAB have now come up with a next-generation set of ad sizes, which are based on a ratio rather than absolute ad sizes (ie 1:1 for a square ad). These new ad sizes are meant to future proof websites against increases in screen resolution, however, they have not as of yet been adopted by many websites (if any). The current set of standard ads are referred to in this new paradigm as “Transitional sizes”, meaning that we should keep using them for now. This is advice that The Online Advertising Guide very much agrees with.



IAB Standard Ad Definition

Glossary Index