Digitaland Advertising Blog

This guide is for the designers and developers who build mobile banners, and for the producers who brief them. It covers each standard size and where it runs. It also covers weight limits and how to keep a banner sharp on high-density phone screens. Every spec comes from an official spec page, linked where it is used.

Mobile banner ad sizes at a glance

Here is which platform lists which size for phones and tablets. The columns come from the Google Ads display specs, the AdMob fixed banner sizes, the Trade Desk creative specification and the Amazon DSP mobile banner specs.

AdMob handles interstitials as their own format, so 320×480 isn’t in its banner table. Google Ad Manager’s interstitial sizes are covered further down. For desktop sizes as well, see our banner ad specs cheat sheet.

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320×50: the standard mobile banner

320×50 is the phone banner that every platform we checked lists. AdMob calls it “Banner” and serves it on phones and tablets. Google Ads lists it as “Mobile banner”, next to its narrower sibling 300×50.

Google Ad Manager notes that app banners are shown in the content stream or as adhesive units. An adhesive unit is pinned to the top or bottom of the screen.

Sticky units come with rules. The IAB New Ad Portfolio allows them only when:

• The ad is less than 25% of the screen height.
• It has a clear boundary that separates it from the content.
• It covers the full width of the screen, edge to edge.
• It has a close button above its top right corner.

The IAB puts 300×50 and 320×50 in the same 6:1 “smartphone banner” group. They are still different pixel sizes. If the media plan lists both, deliver both.

320×100: the large mobile banner

320×100 doubles the height of the standard banner. AdMob calls it “Large banner” and serves it on phones and tablets. Google Ads lists it as “Large mobile banner”.

The extra 50 pixels make room for a product shot beside the headline. That suits product-led messages.

It is not universal, though. It isn’t in The Trade Desk’s smartphone static list. It isn’t in Amazon’s mobile banner table either. Confirm it with the media plan before you build it for programmatic buys.

300×250 on mobile: the in-feed size

The medium rectangle is the size that crosses screens most easily. AdMob serves its 300×250 “IAB medium rectangle” on phones and tablets. Google Ads calls the same size “Inline rectangle”.

The Trade Desk lists it for both smartphones and tablets. Amazon DSP lists it for mobile, with artwork at 600×500 and a 40 KB static limit. On a phone it usually sits between paragraphs or posts as the reader scrolls.

Because one 300×250 can run on desktop and mobile, it is often the best value in a banner set. Our 300×250 ad size guide covers its specs and layout in detail.

320×480: the mobile interstitial size

Interstitials fill the screen between two moments of content. Google Ad Manager traffics interstitials in these sizes:

• Phones: 320×480 portrait or 480×320 landscape.
• Tablets: 768×1024 portrait or 1024×768 landscape.

On Ad Exchange, the request is the size of the device screen, and the buyer can return a smaller creative within a range. Google’s own example: a 320×480 screen accepts creatives from 160×192 up to 320×480.

The Trade Desk lists 320×480 for smartphones, and tablet interstitials at 1024×768 and 768×1024. If you plan richer full-screen work, our guide to rich media formats in mobile advertising explains the options.

IAB mobile ad sizes: fixed sizes vs flexible ratios

The IAB’s 2017 portfolio moved from fixed sizes to aspect ratios. Fixed sizes such as 320×50 stay as “transition” sizes, mapped to the nearest ratio. The 6:1 smartphone banner, for example, flexes from 300×50 up to 450×75.

Here is how the familiar mobile sizes map:

The IAB measures these in density-independent pixels (dp). Its own example: 320 dp is about 2 inches wide, and on a screen with a pixel density of 2, 320 dp equals 640 real pixels. That one line explains the whole retina question below.

Tablets mostly reuse desktop sizes. AdMob serves 468×60 and 728×90 on tablets only. The Trade Desk’s tablet list adds 160×600 and 336×280. For the full IAB list, see our IAB standard banner sizes guide, and for layouts that adapt across devices, our cross-screen HTML5 best practices.

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Retina and 2x: getting the banner ad size for mobile right

Phone screens pack more physical pixels into each CSS pixel. MDN notes that a devicePixelRatio of 2 is expected on HiDPI or Retina displays, and modern phones often go higher. An image drawn at exactly 320×50 pixels will look soft on those screens.

Amazon makes 2x a rule for two sizes. Its 320×50 must be designed at 640×100, and its 414×125 at 828×250. For its other mobile banners, 2x is recommended but not required. Amazon also sets a minimum font size of 16pt at 2x.

Sharpness has a price. Doubling width and height gives four times the pixels, and file weight follows. Here is how we keep 2x banners light:

• Use SVG for logos, icons and shapes. They stay sharp at any density.
• Set headlines and buttons as live text, not baked into images.
• Save 2x only for photos and product shots, then compress them hard.

Mobile banner weight limits by platform

Size is half the spec. Weight is the other half, and it is a common reason creatives get sent back.

When one banner set runs on several platforms, build to the strictest limit on the plan. That avoids a second round of exports. If a banner comes in heavy, our tips to reduce HTML5 banner size will help.

How to build a mobile banner set that passes QA

Many mobile problems start with the brief, not the code. This is the order we work in.

1. Get the size list per platform. A Google Ads plan and an Amazon plan won’t ask for the same sizes.
2. Design 320×50 first. Then scale up to 320×100, 300×250 and 320×480.
3. Ask for 2x source art. Upscaling 1x images never looks sharp.
4. Build at 1x with 2x assets. Check weight against the strictest spec.
5. Build for the right environment. The Trade Desk notes that web browser creatives don’t work in apps. In-app rich media uses MRAID, and TTD supports versions 1.0 and 2.0.
6. Test on real phones. Read the smallest text at arm’s length.
7. Make the static versions last. Backups and static uploads should show the final frame of the finished ad.

That last step multiplies fast on a big campaign. Our free tool turns a finished HTML5 ZIP into backup images, GIFs and MP4s, so the static set doesn’t need a second design pass. For the GIF side, see how to convert an HTML5 banner to GIF.

Before delivery, check each size against this list:

• The ad’s dimensions match the slot exactly, at 1x.
• Images inside are 2x, or SVG.
• Smallest text is readable on a real phone.
• File weight is under the strictest platform limit.
• A light background has a visible border. Amazon recommends a non-white 1px border or a dark background.
• Web and in-app versions are built for their environment.
• Static versions are at the size each platform asks for.

If your team would rather hand off the build, an HTML5 banner production company can deliver the full set to each platform’s spec.

7 mobile banner mistakes we see in QA

1. Delivering a 640×100 HTML5 ad for a 320×50 slot. The artwork is 2x. The ad is not.
2. Upscaled artwork. A 1x image stretched to 2x looks blurry on every modern phone.
3. Text too small to read. Amazon sets 16pt at 2x as the floor. Check it on a real phone.
4. Ignoring the weight of 2x images. Four times the pixels can push a 320×50 past 50 KB.
5. Assuming 320×100 runs everywhere. Some DSP specs don’t list it.
6. No edge on a white ad. On a white page, the banner disappears into the content.
7. A web tag in an app. Web browser creatives don’t work in apps on The Trade Desk.

Frequently asked questions

Sources

• Google AdMob: Set a fixed banner size
• Google Ads: display ad requirements and sizes
• Google Ad Manager: How mobile app interstitials work
• Google Ad Manager: Ad formats and sizes for mobile app
• IAB New Standard Ad Unit Portfolio (PDF, July 2017)
• Amazon Ads: Mobile app static banner ad specs
• The Trade Desk Creative Specifications (PDF)
• MDN: Window.devicePixelRatio