Digital banner ads require special sections on a publisher's website to be displayed. Normally, this section is determined by the publisher/content creator but the size of that section is usually predefined. This space where the banner ad will be displayed is called an ad slot.

Adslots dictate the experience of the visitor and it is the responsibility of the publisher to make them non-intrusive. For that matter, it is important for the publisher to understand the various dimensions of ad slots and where they have shown optimum performance.

The Leaderboard (728×90)

The leaderboard format is a standard banner ad size that works really well as a website header. These ad formats utilize both text and images. Mobile ads aren’t supported.

Advertisers love the leaderboard largely because it fits well before or immediately after the website header. And, since advertisers are fond of this Adsense banner size and format, more ads are created in this size. Because of this, the leaderboard ads tend to be of better quality.

This Adsense size performs well on most websites due to its size and placement above the fold.

The Large Rectangle (336×280)

Large rectangle ads are, as their name suggests, larger and more noticeable. Unfortunately, due to their size, they might not fit in the sidebar for all website themes. Placing this ad in a sidebar that isn’t as wide as the large rectangle Adsense format could cause the content to be distorted, disrupting the user experience. This ad format is also not mobile optimized.

Large rectangle Adsense banners support both image and text ads and are ideally placed in between paragraphs or other content vertically, rather than squeezing them into a sidebar. Thanks to its size and placement options, this is one of the highest-performing Adsense banner sizes and gets a better ad inventory.

The Medium Rectangle (300×250)

The medium rectangle ad format works for both text and display ads and can also be used in mobile page layouts. At a width of 300px, this banner size will typically fit into a sidebar or within the content area of a website without impacting user experience.

Thanks to its versatility, the medium rectangle ad format gets a large ad inventory, translating to better-paying ads for you. Rumor has it this is the ad size that brings in the best click-through rate for more sites.

The Large Mobile Banner (320×100)

The large mobile banner is the first mobile-specific ad to make our list of the highest-performing banner sizes and formats. It works best when displayed at the top of the page, just underneath the site header. You can also place it farther down the page and throughout content for an effective ad that has less impact on user experience.

As more and more website traffic comes from mobile devices, advertisers are focusing on creating more and more mobile ads. That means this ad format brings a better ad inventory with it.

The Half Page or Large Skyscraper (300×600)

The large skyscraper Adsense banner size is a wide vertical banner. It’s sometimes referred to as the “half-page” due to its large size. As you can probably guess, its size is what makes this one of the highest-performing Adsense banner sizes and formats. It’s a favorite among advertisers that need more space to share their message.

More and more publishers are opting for this ad size, too, since it draws more attention. That can translate into more clicks and higher revenue. It really comes down to whether or not the ad size fits your website. If so, it can make a great addition to your sidebar.

The Wide Skyscraper (160×600)

This ad format is a vertical banner that’s designed with narrow sidebars in mind. It uses both text and image ad formats and is a favorite with advertisers and website owners. Since it fits in narrow sidebars, site owners find it to be less disruptive to user experience.

Since it’s about half the width of the large skyscraper ad format, it’s less intrusive and will draw less attention.

The Mobile Leaderboard (320×50)

The mobile leaderboard is the second mobile-specific banner format on our list. It’s about half the height of the larger mobile ad format, making it a little less effective for earnings but offering a better user experience on smaller mobile devices. If you find that your mobile viewers are visiting from these smaller devices, this ad will be a much better option for you. And, since mobile ads are popular with advertisers, rest assured you’ll enjoy a large ad inventory.

The Billboard (970×250)

Billboards are another large banner format that is best placed at the top or bottom of your webpages. Due to its size and placement options, you’re likely to see better ads. However, this ad type does have a smaller inventory. While it is a great ad size for certain keywords, you may struggle with the limited inventory.

The Square (250×250)

This is a small banner size. Not the smallest. The advantage of smaller ads is that they’re more likely to fit into your site’s design than some of the larger ads on our list. However, larger ads tend to be much more noticeable. If your design doesn’t have a lot going on, this might be a good option you could plug in just about anywhere. Of course, being a smaller ad, you’re going to end up with a smaller ad inventory.