Display advertising in 2021: Size Matters (Part 2)

July 26, 2021

Welcome to part 2 of our article about display ad sizes in 2021. In Part 1 we discussed the basics of display advertising and the most popular desktop display ad sizes for this year. If you still haven’t read it yet, you’re missing out on some useful tips and tricks, just saying.

Although there are still some people that use desktop devices more than mobile, mobile web traffic accounts for 52.6 percent of the global web traffic, as oberlo.com shares. Therefore, in this article, we’ll be focusing on the best sizes for mobile display ads in 2021. We’ll be also looking at some key display ads types, so grab a notepad, and let’s get started.

Mobile Ad Size Cheat Sheet

As you probably know, marketers and business owners alike are prioritizing mobile over desktop and always optimize their ads for mobile users first. For the past year, the world gained 93 million new mobile phone users and now we’re looking at an audience of 5.22 billion unique mobile users. As DataReportal shares, that’s an increase of 1.8% in comparison to the same period in 2020. When it comes to mobile display ads, one great feature is that they can be shown not only while the user is browsing the web, but also in apps. And although some sizes work great both on desktop and mobile devices (such as the Medium Rectangle), there are specific sizes only for mobile users:

Mobile Leaderboard

This is the most effective and popular size for mobile display ads. Similar to the desktop version, it’s a horizontal stripe, however, on mobile it covers the full width of the screen, being 320x50px. It accounts for 12% of all impressions globally and can be used in apps as well as in the browser. This format is often placed at the bottom of the screen, but it can also be a good top-of-the-screen option. Keep in mind that when using this format you need to make sure that your texts and CTAs are big enough to be readable.

If you want to have more room for creativity, you can opt-in for the Large Mobile Banner instead. Its size is 320x100px, which allows for more visuals or text to be included. It’s not as popular as the Mobile Leaderboard, but it’s still one of the top five most deployed mobile ad sizes. An important note, which we must mention is the fact that currently the Large Mobile Banner can be used only within the Google Display Network, so if you’re using another advertising platform, then you should avoid this format.

Mobile Full Page Flex

The Mobile Full Page Flex format refers to a responsive ad format, which can dynamically adapt to the entire available advertising space while maintaining the same aspect ratio. Therefore, in this case, the size does not matter (yes, yes, we know we said it matters but this format is an exception). That being said, advertisers must make sure that the ratio of their creative is 1:1 (for example 300x300px; 320x320px, 500x500px, etc.) This is an official ad format, defined by IAB as a creative “full-screen ad experience with sight, sound, motion, and interaction capabilities”. This format can be used in two ways: The ad can either run at a specific time set (for example in-app ads while the application is loading), or it can be triggered by users when they click on a CTA of another ad. For example, you can create a mobile leaderboard ad with the following CTAs: “click here for more information” or “swipe up for details”. When the user clicks or swipes, this action will trigger the full page flex ad and it will be displayed on the device’s screen.


This format is a good alternative to rectangular formats. That being said, the square format is not as popular as the others on our list and can prove to be hard to master as it is quite small – 250x250px. That is why you should carefully consider your visuals and text if you decide to use this format.

The Small Square is even a smaller version of the Square with dimensions 200x200px. Keep in mind that if you use this format your ad performance may be restricted due to the limited supply of display ad space for this specific ad size.

Aside from the size of your display ads, you should also consider the creatives with which you’re going to promote your product. What images will you use and what text should you include? Should you use a static picture or a video? Those are important questions that you must answer in order to create a successful ad that is tailored to your campaign goals. To help you out, we’ve decided to list some of the popular display ad types, so you can decide which of them might work best for you.

Display Ads Types

Did you know that the average person is now estimated to encounter between 6,000 to 10,000 ads every single day? This shocking data is shared by ppcprotect.com. They also inform us that back in the 70’s people saw between 500 and 1,600 ads daily. Given this data, it’s not hard to assume that today marketers need to put much more effort into grabbing user’s attention than 50 years ago. And while a lot of factors play a role when it comes to the creation of enticing ads, the ad type is arguably an essential point that you need to think about. Some of the most popular display ad types in 2021 are:

  • Static

Static ads are simple banner ads that consist of an image and text. They do not work with additional media such as audio or video. As you already know, static ads come in different sizes and shapes and continue to be used by hundreds of thousands of brands worldwide. They are the easiest to make but don’t come without drawbacks. One limitation of static ads is the fact that they are often ignored by the reader because a static image needs to be really creative to capture users’ attention. Additionally, static ads are more or less one-way communication, as they are less interactive than other ad types.

  • Animated 

As the name suggests, animated ads usually consist of image/s that move. So for example, an animated display ad could have a static background image with only one or two elements blinking or moving. Additionally, you could create an animated ad, in which all parts of the image perform some kind of movement. Animated ads are much more successful in grabbing user’s attention than static ads because people tend to notice movement with their peripheral vision. So even if a given person is not looking directly at the ad, he/she is going to be constantly reminded of the creative because of its movement, and sooner or later the user’s curiosity will push them into investigating your offer.

  • Video 

Video ads are another great type of display ads. They are quite similar to animated ads because both types involve moving pictures or objects. In that sense, video ads are great for attracting the attention of your target audience. Not to mention that video is the king when it comes to marketing in 2021, as more and more consumers prefer watching instead of reading. Furthermore, as WordStream shares, viewers retain 95% of a message when they watch it in a video compared to 10% when reading it in text. (We might come up with a quiz to prove that’s not the case for Marception Blog’s readers, so pay attention guys! Just kidding… or are we???)

  • Interactive 

If you want to create a truly memorable ad, interactive ads are your best choice! Those ads require the user to take a certain action, for example, play a short game (this approach is often seen in mobile app application ads). Additionally, interactive ads could include quizzes, polls, and other lead forms. As HubSpot shares, 73% of businesses agree that combining traditional content marketing tactics with interactive content enhances the retention of their organization’s message.

  • Lightbox

Last but not least, lightbox ads can enable you to offer immersive experiences to your target audience. This type of display ad looks just like a regular static ad, however, when the user hovers their mouse over it, the ad expands and takes up a much bigger space of the display. Once the ad has expanded it transforms from a practically static ad to a comprehensive sensory experience for the user. You can add audio, video, animation, or even interactive elements to your lightbox ads. To avoid accidental engagement with the ad, the expansion functionality only works when the user hovers their mouse for two seconds over the banner, as TechCrunch explains. The source also states that lightbox ads grant an engagement that is 6 to 8 times higher than the one of standard click-to-expand ads.

Though we have listed some of the most popular display ad types, we couldn’t include all the options available to marketers and advertisers. Furthermore, innovative sizes, formats, and creatives are being introduced to us daily. Therefore, you need to keep up with the advertising trends and perform comprehensive research before you settle on the right ad type and format for your campaign. If you need help with the planning, implementation, and analyses of your display ad campaigns, Interval is always ready to help you. As a digital marketing agency, we are passionate about creating content, running advertising campaigns, and optimizing our clients’ digital performance. Contact us for a free consultation now.

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