Definition
A banner is a display unit whose size is fixed by the publisher's slot and whose content is entirely the advertiser's: a JPG, PNG or GIF, or an HTML5 creative that animates. The IAB standardized the common sizes so that one creative set runs across thousands of sites; the medium rectangle (300×250), the leaderboard (728×90), the mobile banner (320×50) and the wide skyscraper (160×600) carry most of the volume on ad networks today.
How banner ads are served
- The publisher reserves a slot of a given size and places the network's tag in it.
- When the page loads, the tag requests an ad for that size, GEO, device and visitor.
- The network's ad server runs an auction among campaigns that have a creative in that size and whose targeting matches, and returns the winner.
- The impression is counted when the creative renders; the advertiser is charged its CPM bid divided by 1,000, or its CPC bid if the visitor clicks.
Sizes and file limits
| Size | Name | Where it runs |
|---|---|---|
| 300×250 | Medium rectangle | Desktop and mobile, in and beside content |
| 728×90 | Leaderboard | Desktop, above the header or content |
| 320×50 | Mobile banner | Phones, top or bottom of the viewport |
| 160×600 | Wide skyscraper | Desktop sidebars |
Networks cap the file size, on Reacheffect 150 KB for JPG, PNG and GIF, so the page stays fast. Static images are moderated faster than animated GIFs because there are fewer frames to review.
Who uses banner ads
Brands that want the visual identity on screen rather than a bare landing page: iGaming operators showing a welcome offer, sportsbooks around match days, finance and trading platforms, game publishers. Media buyers also use banners as the brand-safe companion to pop and push campaigns running on the same offers.
Related terms
| Term | Relation | Where defined |
|---|---|---|
| Native advertising | Display alternative styled by the page | Term page |
| CPM | Pricing model | Term page |
| Ad server | What delivers the banner | Term page |
| CTR | Click performance | Term page |
FAQ
Which banner size performs best?
The 300×250 medium rectangle carries the most inventory and the most clicks because it runs on both desktop and mobile and sits inside content. Supply the four standard sizes to reach all slots.
Are banner ads CPM or CPC?
Mostly CPM on ad networks, because the publisher is paid for the space whether or not the visitor clicks. Some networks also offer CPC bidding on banners.
What file formats are accepted?
JPG, PNG and GIF within the network's file-size limit; many networks also accept HTML5 zips for animated creatives, subject to moderation.