The banner is the oldest and most familiar mobile ad format. It is a small rectangular unit, typically 320x50 pixels, pinned to the top or bottom of the screen while the rest of the app carries on above or below it. Because it is always on and easy to drop in, almost every ad-supported app has run one at some point.

How it works

A banner occupies a fixed slot in the layout and refreshes on a timer, serving a new creative every 30 to 60 seconds. It is priced mostly on CPM, the cost per thousand impressions, so the publisher earns a little each time the unit is shown. Since the ad is passive and shares the screen with real content, advertisers pay modest rates for it, which keeps the eCPM low compared with formats that command full attention. Common sizes include the 320x50 standard banner and the larger 300x250 medium rectangle, and modern SDKs offer adaptive banners that size themselves to the device. Viewability feeds the price too, since a banner scrolled off-screen or hidden behind other elements earns little even when it technically loads.

Banner ad vs. other formats

The trade-off is attention. A banner never interrupts the session, which is why it feels unobtrusive, but that same quality means users learn to ignore it, an effect known as banner blindness. An interstitial ad takes the opposite approach, filling the screen at a natural break and earning far more per impression. An offerwall goes further still: it is opt-in and rewards the user for completing an action, so it earns on engagement rather than passive views. Banners win on simplicity and consistency, and they lose on value per impression.

Where banners fit for publishers

Banners are a steady, low-friction revenue floor. They rarely move the needle on their own, but they run quietly in the background and add incremental income without demanding design changes to the app. Most publishers treat them as one thin layer in a wider stack, sitting beneath higher-value formats rather than carrying the monetization alone. They also serve as a reliable fallback: when no higher-value ad is available to show, a banner can still fill the slot and earn something rather than nothing.

Banners and the offerwall

Because a banner earns so little per impression, publishers usually pair it with formats that convert attention into real revenue. An offerwall is a common companion. It sits behind a dedicated entry point, asks nothing of users who are not interested, and pays out strongly when someone completes an offer. A banner keeps a small amount of revenue flowing at all times, while the offerwall captures the high-value engagements the banner never could. Run together, they cover both ends of the value range.

Common mistakes to avoid

• Stacking or refreshing banners too aggressively to chase impressions, which annoys users and can breach network policies.

• Judging a banner by impression count alone. High impressions at a low eCPM can still add up to very little.

• Relying on banners as the primary revenue source instead of layering higher-value formats on top.