What is a 336×280?
The 336×280 is an ad unit that has been delisted by the IAB. It has dimensions of 336 pixels wide by 280 pixels tall. 336×280 ads are also known as a Large Rectangle (or LREC). As the name implies, it is essentially the big brother to 300×250 (or Medium Rectangle) ad unit.
The 336×280 ad can be run in its own ad slot but is more commonly set up as a multi-sized ad slot along with a 300×250.
The 336×280 large rectangle is a highly successful ad unit on AdSense. This is both in terms of performance and the eCPM it commands. However, it is not very common on other ad networks. This is why it was delisted by the IAB in 2011 in favour of the 300×250 ad unit.
An LREC is usually placed on the side of content, in the same place an MPU would be. When no Large Rectangle is available to deliver, AdSense will show a centred 300×250 instead.
What it looks like
The LREC dimensions are 336 x 280 pixels. Below is a live example of this ad unit.
Note: The live ad may not always load for technical reasons, and instead a backup image will show.
336×280 Advice for Site Owners
If you are using AdSense as your Ad Network, you can generally expect a very high CPM for 336×280 ads, but perhaps less than a 300×250. However as 300x250s can appear within this space, if your site looks good with this ad size it is probably worth pursuing.
This ad unit is rarely used outside of AdSense. This means if you are selling ads to multiple ad networks this ad size might cause you problems. The best way to manage this is to make sure your 336×280 ad slot is used as a multi-sized ad slot with a 300×250 so you don’t have to worry about editing your site.
As this ad unit is the same aspect ratio as the very popular 300×250, it wouldn’t be surprising if it made a comeback in the coming years, as increasing screen resolutions will once again mean old sizes seem smaller.
336×280 Advice for Ad Buyers
This ad unit is usually very successful when used well so should be considered for an ad buy. It is often reasonably priced as there is sometimes less competition for this ad size. However, in many cases, you can expect to pay the same CPM or CPC as an MPU, as that is what you will ultimately be competing with.
As this ad size has the same aspect ratio as a 300×250, it should be very easy to design. If you are already creating an MPU, it can simply be scaled up. This makes the costs for creating this extra ad unit as minimal as can be.
336x280s are not very prevalent across the internet. This means this ad unit should usually only be created when there is at least one specific placement you intend to run it on.
Tip: A 336×280 is essentially a large MPU, so it should be used for interactive or video ads to get the most out of it.