Most ad formats are designed and then placed. A responsive display ad works the other way round. You give Google a collection of pieces, pictures in two shapes, logos, a handful of headlines and descriptions, a business name, and Google assembles an ad to fit whatever slot it is serving into: a rectangle beside an article, a banner across the top of a page, a strip at the bottom of a phone screen, or a text ad that uses none of your pictures at all.
That is useful, because one set of assets reaches thousands of sites and apps in every size. It is also where most weak display campaigns come from, because the assets were made as if they were a finished ad. The figures here are from Google Ads Help and the Google Ads API documentation, checked in September 2026.
The pieces Google asks for
- Landscape images at 1.91:1: 1200 by 628 recommended, 600 by 314 at least, up to 5 MB each.
- Square images at 1:1: 1200 by 1200 recommended, 300 by 300 at least. One Google spec page gives 600 by 600 as the recommended square, the other 1200 by 1200; the larger is the safer choice.
- Up to 15 landscape and 15 square images, according to Google's spec page; its best practice guide suggests 5 to 10 of each, and adds vertical 9:16 images at 900 by 1600.
- Logos: a square logo at 1200 by 1200 (at least 128 by 128) and a wide 4:1 logo at 1200 by 300 (at least 512 by 128), up to 5 of each.
- Short headlines: up to 5, of 30 characters each.
- One long headline of up to 90 characters, and up to 5 descriptions of up to 90. One Google guide gives the description limit as 80, so writing to 80 is the safe choice.
- A business name of up to 25 characters.
- Optionally, videos at 16:9, 1:1 or 2:3.
Google mixes these for every impression. A short headline may be shown with any of the descriptions, next to any of the pictures, under either logo. So each piece has to make sense on its own, and in any combination. A description that only works after one particular headline will eventually be shown after a different one.
How the ad is put together
Google says plainly that it will adjust the size, appearance and format of a responsive display ad, and that the same ad can appear as a picture banner on one site and as a text ad on another. It does not publish a template for each size, and in practice the layouts vary. Some patterns are common.
- A 300 by 250 rectangle usually shows a landscape picture on top, with the logo, a headline, a line of description and a button underneath.
- A 728 by 90 leaderboard has room for a square picture or logo on the left, the words in the middle and a button on the right.
- A 320 by 50 phone banner fits little more than a logo, a short headline and a small round button.
- A 300 by 600 half page stacks the logo, a landscape picture, the long headline, a description and a full-width button.
There are also two families of layout. Native ads are styled by the publisher to match the site they sit on, fonts and colours included. Non-native ads are built by Google, using the main and accent colours you set or, if you allow flexible colour, colours Google picks. Turning flexible colour off rules out the native layouts, which narrows where the ad can run.
Where display ads are bought now
Display is in the middle of a move. Since April 2025, image ads in Demand Gen campaigns have been able to serve on the Google Display Network, alongside YouTube, Discover and Gmail, with channel controls to choose among them. In June 2026 Google began rolling out a tool to migrate standard Display campaigns into Demand Gen. It says new Display campaigns will in time be created only inside Demand Gen, with the rest migrated automatically, and that the move should be finished in 2027. Display-only campaigns remain possible there, responsive display ads and uploaded image ads are both supported, and manual CPC bidding is not. The asset rules in this article apply either way.
Why text on the picture backfires
The most common mistake is to treat the landscape image as a finished banner, with the headline, the price and the logo designed into the picture. Google advises against it for a simple reason: it crops, shrinks and reuses the images across every size, and it adds its own headline and logo beside them. Words baked into the picture end up cut in half at the edges, too small to read in a phone banner, or printed twice, once in the image and once in the ad.
Use pictures that work as pictures: the product, the place, the person using it, with the subject near the middle and some room around it. Put the words in the text fields, where Google can set them at a readable size for each slot. If a client insists on a designed banner, upload it as an image ad instead.
Uploaded image ads are a different product
An uploaded image ad is shown exactly as designed, but only in slots of its exact size. Google accepts GIF, JPG and PNG files of up to 150 KB, with animation of up to 30 seconds that runs slower than 5 frames a second. The common sizes are 300 by 250, 336 by 280, 728 by 90, 300 by 600, 160 by 600, 970 by 250, 320 by 50 and 320 by 100, with a longer list of less common ones. Many advertisers run both: a responsive ad for reach, and a small set of designed banners for the sizes that matter most to them.
HTML5 banners are a separate case again: up to 600 KB, and only for accounts older than 90 days with more than 9,000 US dollars of lifetime spend, according to Google's image ad rules. Google says HTML5 support in Demand Gen is due in late 2026.
Buttons, headlines and the words that get cut
The call to action is set to Automated by default, which lets Google choose. You can pick one instead from Google's list: Learn More, Shop Now, Sign Up, Book Now, Contact Us, Apply Now, Get Quote, Subscribe, Download, Install, Visit Site and See More. There is no Order Now; Shop Now is the nearest.
Short headlines are hard limits: Google Ads will not accept a 31st character. Write them to be read in a banner at a glance, and use the long headline for the version that can breathe. Test the business name too; at 25 characters, a long legal name will not fit, and the trading name reads better anyway.
Google rates each responsive ad from Poor to Excellent for ad strength, and says that adding horizontal, square and vertical images helps. The rating is a guide to how many combinations Google has to work with, not a forecast of results, but a Poor ad usually means too few pieces.
The small triangle in the corner
Display ads carry Google's AdChoices marker in the top right corner: a small blue triangle with an i in it, about 19 by 15 pixels, which expands to the word AdChoices when someone points at it. Clicking it opens Google's About this ad page. Beside it sits a close control that lets people stop seeing the ad and say why. Keep the top right corner of your pictures free of anything important, because it is often covered.
A checklist before the campaign goes live
- Landscape and square versions of every picture, with no words baked in and the subject in the middle.
- Both logos, on a transparent or plain background, readable at small sizes.
- Five short headlines that each stand alone, one long headline, and descriptions that do not depend on each other.
- UTM tags on the final URL, so display traffic is not lost as direct in the client's analytics.
- A look at the ad in the common sizes before launch.
The ad mockup generator on this site shows the same assets as a 300 by 250, a 728 by 90, a 300 by 600 and a 320 by 50 phone banner, in the layouts Google commonly uses, with the AdChoices corner. It will not predict every layout Google chooses, but it catches a headline that does not fit or a picture that does not crop, which are the problems that cost the most.
