Format & Device Testing with Image Ads

Erin Spradlin

June 10, 2014

Format & Device Testing with Image Ads

Chances are you have heard of A/B ad testing because marketers love A/B ad testing the way miller moths love my apartment. In case you haven’t though, this is the practice of always displaying at least two versions of your messaging, and moving forward with the one that performs better. Marketers should always be in the process of A/B ad testing and moving toward the messaging that most resonates with their target demographic. This is pretty basic in AdWords and a well-established best practice when writing text ads, but image ads are often overlooked.

Image ads that show on the Google Display Network have limitations. They must be 150 KB or less in one of the following formats: .GIF, .JPG, .JPEG, .PNG and/or .SWF. Additionally, they must conform to one of the following sizes:

  • 120 x 600
  • 160 x 600
  • 200 x 200
  • 250 x 250
  • 300 x 250
  • 300 x 600
  • 320 x 50
  • 320 x 100
  • 336 x 280
  • 468 x 60
  • 728 x 90
  • 970 x 90

PPC managers are limited in their ability to manipulate image ads because they are static and supplied by the client for uploading. Nevertheless, you can still perform format and device testing on image ads. This can either be done by performance based on the language in the ads or size and shape of the ads.

This past year, I ran a large performing arts account that had numerous campaigns for different shows. Each of these shows incorporated image ads with identical or similar text and the same call to action in every format. The ads were all in the first position and the sizes that ran were: 160 x 600, 300 x 250 and 728 x 90. (Below you will see the data in two ways; the first is broken out by device and the second is broken out by image ad size.)

By Device

By Image Size

The results show that different ad sizes perform different on different devices. For instance, the 300 x 250 ad has a CTR of 0.41% in the mobile space and only a 0.06% CTR on desktop and a 0.24% CTR in Display. The disparities in performance create an argument for creating mobile-campaigns (to the extent that can be done with bidding) and performing size-based optimization for different devices.