Google Display Ad Sizes: Which Formats Actually Perform

Google Display Ads run across a network of over two million websites and apps, and the size you choose directly affects where your ad appears, how often it serves, and what it costs. The most important sizes are the 300×250 medium rectangle, the 728×90 leaderboard, the 160×600 wide skyscraper, and the 300×600 half page. These four cover the majority of available inventory and should form the foundation of any display campaign.

But knowing the dimensions is the easy part. Knowing which sizes to prioritise, why some consistently outperform others, and how to think about display creative as a commercial asset rather than a design exercise , that is where most advertisers leave money on the table.

Why Ad Size Is a Strategic Decision, Not a Production Detail

Early in my career, I watched creative teams spend weeks debating colour palettes and copy hierarchy on display ads, while the media buyer quietly ran everything in a single 300×250 format. The campaign underperformed. The post-mortem blamed the creative. Nobody questioned the fact that they were competing for a fraction of available inventory because half the required sizes were never built.

Ad size determines inventory access. If you are only running one or two formats, you are locked out of placements that your competitors can reach. That is a structural disadvantage that no amount of creative refinement will fix.

Google’s Display Network is vast. Understanding how it fits into a broader paid media strategy is worth the time. If you are building out your paid advertising knowledge from the ground up, the Paid Advertising Master Hub covers the full picture, from search to social to programmatic.

The relationship between format and placement is also a relationship between format and cost. Larger, higher-impact formats in premium placements carry higher CPMs. Smaller formats in remnant inventory are cheaper but often deliver lower intent audiences. Neither is inherently better. The right choice depends on your objective, your budget, and where your audience actually spends time online.

The Core Display Ad Sizes and What Each One Does

Google publishes its own guidance on recommended ad sizes, and the list has remained largely stable for years. The formats below are the ones that matter most in practice.

300×250: The Medium Rectangle

This is the workhorse of display advertising. It appears in sidebars, embedded within content, and at the bottom of articles. It works on both desktop and mobile. Publishers love it because it fits almost anywhere. Advertisers use it because it has the widest reach across the network.

If you are only going to build one size, build this one. But if you only build this one, you are leaving significant inventory on the table.

728×90: The Leaderboard

The leaderboard sits at the top or bottom of a webpage, typically above the fold on desktop. It is one of the most recognised display formats and one of the most commonly requested by publishers. It does not translate to mobile, so its reach is limited to desktop and tablet inventory. For campaigns with a desktop-heavy audience, it remains highly relevant.

160×600: The Wide Skyscraper

The wide skyscraper runs vertically down the side of a page. It has less inventory than the medium rectangle or leaderboard, but it is persistent on longer pages because it stays in view as users scroll. For brand awareness campaigns where repeated exposure matters, this format earns its place in the mix.

300×600: The Half Page

The 300×600 is the format most advertisers skip and most should not. It is large, visually dominant, and commands attention in a way that smaller formats simply cannot. Publishers who support it tend to be premium properties. The CPM is higher, but the engagement rate often justifies it. In my experience running campaigns across retail and financial services, the 300×600 consistently punched above its weight when the creative was built specifically for the format rather than adapted from a smaller size.

320×50 and 320×100: Mobile Banners

These are the dominant mobile display formats. The 320×50 is the standard mobile banner, appearing at the top or bottom of a screen. The 320×100 is the large mobile banner, offering twice the height and more creative space. With mobile accounting for the majority of web traffic in most categories, ignoring these formats is a significant oversight.

I have reviewed campaigns where mobile impressions represented over 60% of total delivery, but the advertiser had only built desktop formats. The system was serving scaled-down versions of desktop creative on mobile devices, and the performance data was being misread as a targeting problem. It was a production problem.

970×90 and 970×250: Large Desktop Formats

The 970×90 large leaderboard and 970×250 billboard are high-impact desktop formats typically found on premium publisher inventory. They are not available everywhere, but where they are available, they offer significant visual real estate. These are worth building if you are running brand campaigns on curated placement lists rather than broad network targeting.

Responsive Display Ads: What They Are and What They Are Not

Google’s Responsive Display Ads allow you to upload headlines, descriptions, images, and logos, and the system assembles combinations automatically to fit available placements. This is genuinely useful for coverage. It means your campaign can serve in formats you have not manually built.

What it is not is a substitute for purpose-built creative. The automated assembly process produces functional ads, not compelling ones. The image crops are sometimes awkward. The headline and description combinations do not always make commercial sense together. And because Google optimises toward combinations that generate clicks, you can end up with high-CTR combinations that do not reflect your brand positioning accurately.

The right approach is to use Responsive Display Ads for inventory coverage while running static ads in the core formats for placements where creative quality matters. Unbounce has a useful breakdown of what makes display ads more profitable, and creative quality relative to format is a consistent theme.

There is also a measurement consideration. Responsive Display Ads make it harder to attribute performance to specific creative decisions because the system is constantly testing combinations. If creative learning is part of your objective, static ads give you cleaner data.

File Formats, File Sizes, and Technical Specifications

Google accepts static display ads in JPEG, PNG, and GIF formats, and animated ads in HTML5. The maximum file size for most static ads is 150KB. This sounds like a technical detail, but it has real consequences.

I have seen campaigns where the creative team produced beautiful, high-resolution ads that exceeded the file size limit. The ads were either rejected outright or automatically compressed by Google’s system, degrading the image quality. Neither outcome was what the client paid for.

HTML5 ads allow for animation and interactivity, which can improve engagement rates in the right context. But they require more production time and carry more technical risk. For most campaigns, well-designed static ads in the right formats will outperform mediocre HTML5 ads. The format should serve the message, not the other way around.

Google’s ad policies also restrict certain types of animation, including ads that flash rapidly or use deceptive design patterns. Understanding what is permitted before production begins saves time and budget. For context on how Google’s advertising policies have evolved, Search Engine Journal has covered historical policy changes worth understanding if you are new to the platform.

How to Prioritise Sizes When Budget Is Limited

Not every advertiser has the budget to produce 15 different ad sizes. When resources are constrained, the question is which sizes to prioritise for maximum inventory coverage with minimum production cost.

The practical answer, based on what I have seen across hundreds of display campaigns, is to build in this order: 300×250 first, then 728×90, then 320×50 for mobile, then 160×600, then 300×600. That sequence covers the majority of available inventory across desktop and mobile. Add the 320×100 if mobile is a significant channel for your audience. Add the 970×250 if you are running on premium publisher placements.

If you are working with an agency or considering bringing in outside support, the question of which formats to prioritise should be part of the brief. A good agency will have a view on this based on your category and audience. If they do not, that is worth noting. Our overview of PPC management services covers what to expect from a managed display engagement, including how creative production is typically handled.

There is also a temptation to produce all sizes at once from a single master design. This works for format coverage but often produces mediocre creative across the board. A 300×600 designed as a scaled version of a 300×250 will not perform as well as one designed specifically for the larger canvas. Where budget allows, format-specific creative is worth the investment.

The Relationship Between Ad Size and Campaign Objective

Display advertising serves different objectives at different stages of the funnel, and the right size mix shifts depending on what you are trying to achieve.

For brand awareness campaigns, larger formats like the 300×600 and 970×250 earn their higher CPMs because visibility and dwell time matter more than click volume. For retargeting campaigns, the 300×250 and 728×90 are typically sufficient because the audience is already familiar with the brand and the ad’s job is to prompt a return visit rather than create an impression.

For prospecting campaigns targeting cold audiences, mobile formats deserve more weight than many desktop-first advertisers give them. I ran a prospecting campaign for a retail client a few years ago where we had built a comprehensive desktop format set but treated mobile as an afterthought. When we rebuilt the mobile creative properly, the cost per acquisition on mobile dropped by a meaningful margin. The audience was there. The creative just had not been built for the environment they were using.

Understanding how display fits into the broader Google advertising ecosystem is also worth the time. Google Adwords, now Google Ads, encompasses both search and display, and the two channels behave very differently in terms of intent, creative requirements, and measurement. Conflating them leads to poor decisions on both sides.

Display Ad Sizes in Context: What the Numbers Do Not Tell You

There is a version of display advertising optimisation that becomes entirely focused on format performance data: which size has the lowest CPC, which has the highest CTR, which drives the most conversions. This data is useful. It is also incomplete.

Click-through rates on display ads are low across the board. That is not a failure of the format. Display advertising primarily works through impression-based brand building, influencing consideration and recall in ways that do not always show up in last-click attribution models. When I was judging the Effie Awards, the campaigns that demonstrated genuine effectiveness were rarely the ones with the most impressive CTR data. They were the ones that showed a coherent connection between media investment, brand metrics, and business outcomes over time.

This matters for how you interpret format performance. A 300×600 might have a lower CTR than a 300×250 but deliver stronger brand recall because of its size and placement. If you are only measuring clicks, you will make the wrong decision about which format to continue running.

For a grounded view of how Google Ads measurement works more broadly, Search Engine Land’s coverage of how Google explains ad ranking and cost is worth reading alongside the Display Network documentation.

The cost side of display is also worth understanding clearly before you start. Google advertising fees vary significantly depending on format, placement, targeting, and competition. Larger formats on premium placements cost more. That is not a reason to avoid them. It is a reason to be deliberate about when and why you use them.

Display Advertising Across Industries: Where Size Choices Vary

Having run campaigns across more than 30 industries, I can say with confidence that the right format mix is not universal. It varies by category, audience behaviour, and the competitive landscape of the specific placements you are targeting.

In financial services, where trust and credibility matter enormously, larger formats on quality publisher inventory tend to outperform smaller formats on broad network placements. The brand environment matters as much as the ad itself. In e-commerce, where retargeting is the primary use case for display, the 300×250 and mobile banner formats do most of the work because the objective is a return visit, not a first impression.

For local service businesses, the calculus is different again. A beauty salon running Google Ads, for example, is primarily interested in local reach and appointment bookings. The display network can support that objective, but the format choices and placement targeting need to reflect a local audience on mobile devices. Our piece on Google Ads for beauty salons covers how local businesses should approach this channel, including where display fits relative to search.

The broader point is that format decisions should be informed by audience behaviour in your specific category, not just by general best practice lists. General guidance is a starting point. Your own campaign data, over time, is the real answer.

When to Test New Formats and When to Leave Well Alone

There is a version of marketing culture that treats format experimentation as inherently valuable. New format, new opportunity, let us test it. I have seen this instinct lead to campaigns that are perpetually in test mode and never actually generate reliable results because the budget is spread too thin across too many variables.

The more commercially useful question is: what problem would a new format solve? If your current format mix is covering the inventory you need and your creative is performing to target, adding a new format for the sake of it is not innovation. It is distraction.

Format testing makes sense when you have a specific hypothesis. You believe the 300×600 will outperform the 300×250 for a brand awareness objective. You think the 320×100 will improve mobile performance because your current mobile creative is underperforming. You want to test HTML5 animation against static creative to see if the production investment is justified. Those are testable hypotheses with clear success criteria.

Clients sometimes ask for innovation in their display strategy without being able to define what problem they want it to solve. I have had that conversation many times. The honest answer is that display advertising is a mature channel with well-understood formats. The innovation that matters is in targeting precision, creative quality, and measurement sophistication, not in chasing new ad dimensions.

For advertisers thinking about how display fits alongside other paid channels, including social, TikTok Ads represent an increasingly important consideration for audiences under 35. The format logic there is entirely different, but the underlying question is the same: does this format reach my audience in an environment where my creative can do its job?

If you are working with or evaluating a PPC agency for your display campaigns, the format strategy conversation is a useful diagnostic. An agency that defaults to Responsive Display Ads without a clear rationale, or that cannot explain why they are prioritising certain sizes over others, is worth questioning. Our piece on what to expect from a PPC agency covers the questions worth asking before you sign anything.

For anyone building out a more comprehensive view of paid media, including how display sits alongside search, social, and programmatic, the Paid Advertising Master Hub is worth bookmarking. It covers the full channel landscape with the same commercially grounded perspective.

A Practical Framework for Building Your Display Ad Size Set

To pull the practical thread together, here is how I would approach building a display ad size set for a new campaign.

Start with the four core formats: 300×250, 728×90, 160×600, and 300×600. These cover the majority of desktop inventory. Add 320×50 and 320×100 for mobile. If your campaign is running on premium publisher placements, add 970×250. Upload Responsive Display Ad assets as a safety net for inventory coverage in formats you have not built.

Design each format specifically for its dimensions rather than adapting from a master size. The 300×600 should use the vertical space deliberately. The 728×90 needs a clear, readable message at a glance. The 320×50 has almost no room for copy, so the visual and brand mark have to carry the weight.

Build in a review point at four to six weeks to assess format-level performance. Look at impression share by format, CTR, and conversion rate where trackable. Be cautious about over-indexing on CTR as the primary metric. Use the data to inform the next creative iteration, not to make immediate cuts to formats that may be doing brand work that does not show up in click data.

For campaigns where display is part of a broader Google Ads strategy, Semrush’s collection of Google Ads tips covers optimisation principles that apply across both search and display. And for a broader view of how paid search and display compare as investment decisions, their SEO vs Google Ads analysis is a useful reference point for channel planning conversations.

Display advertising rewards consistency and patience more than most paid channels. The campaigns that perform best over time are the ones built on a solid format foundation, with creative that is designed for its environment and measurement that is honest about what display can and cannot prove.

About the Author

Keith Lacy is a marketing strategist and former agency CEO with 20+ years of experience across agency leadership, performance marketing, and commercial strategy. He writes The Marketing Juice to cut through the noise and share what works.

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