What “IAB Standard Banners” Look Like on a Modern Website

Doug Bishop

August 27th, 2025

In the evolving landscape of digital publishing, display advertising remains a vital revenue stream. However, the way ads are presented and filled has transformed over the past decade. It is essential for publishers to grasp the significance of iab standard banners, recognize their presence on websites, and understand their impact on monthly earnings.

The Basics: What Are IAB Standard Units?

The Interactive Advertising Bureau (IAB) created a set of standardized ad sizes so that advertisers and publishers could trade inventory without constant custom work. The most common include:

These iab standard banners ensure consistency and reliability in online advertising.

These iab standard banners play a crucial role in maintaining uniformity and dependability within the realm of online advertising.

• 728×90 – Leaderboard
• 300×250 – Medium Rectangle
• 160×600 – Wide Skyscraper
• 300×600 – Half Page
• 970×250 – Billboard
• 320×50 / 300×50 / 320×100 – Mobile Banner

These units are baked into virtually every ad server and SSP, which means they are the default currency of display advertising. Hundreds of millions of advertisers around the world bid on ads in these slots every single impression. Programmatic Advertising is Traded Electronically in real-time. Not unlike how the Stock market is largely dominated by High Frequency Trading.

How Prebid Changed the Game

Before header bidding, publishers had to set fixed prices in GAM for Networks that wanted to buy. Google’s Ad Exchange was allowed to bid in real-time. As explained in our earlier post on header bidding, this left publishers exposed to waterfall inefficiencies—one buyer at a time, with limited competition.

Google did not have to compete to buy the best impressions.

Enter Prebid.js. By allowing multiple SSPs to bid in real time for the same IAB units, Prebid turned those humble rectangles and leaderboards into battlegrounds where dozens of buyers compete simultaneously for every impression.

The result: vastly higher CPMs and more transparency.

Why IAB Standard Units Matter for Revenue

Most publishers find that 60-80% of display revenue still flows through IAB units. Why? Because these units:

• Have the broadest demand from DSPs and SSPs.
• Are universally supported in programmatic pipes.
• Perform well across both direct and programmatic deals.

Even if you run premium formats (outstream video, native, interscrollers), your bread and butter is still the Adhesion units and the medium rectangle tucked inside articles.

Where the Money Comes From

Your IAB units get filled from a mix of demand sources:

• SSPs (Magnite, Index Exchange, OpenX, Xandr, PubMatic) through Prebid and GAM.
• Google Ad Exchange (AdX), still the single largest backfill source.
• Amazon Publisher Services (APS), which bids directly into your header for standard display units.
• Direct deals with advertisers or agencies trafficking campaigns through your GAM line items.

Each impression is an auction where these buyers compete. The highest net bid (after fees, floors, and ad server logic) wins, and that winning ad is what your reader sees.

Key Takeaway

IAB Standard ad units may look boring compared to shiny new formats, but they remain the foundation of publisher monetization. These units remain the same, even if you have entirely new bidders participating in the auction. Understand them, measure them, and optimize them. Because as long as demand runs through Prebid, GAM, and SSP pipes…

You never know, the simple 300×250 may be responsible for keeping the lights on every month.