Reference
Banner ad sizes: the only six that matter
The IAB lists dozens of display formats. In practice, six sizes carry almost all of the traffic. Here's each one, where it works, and what to put in it.
Leaderboard
728 × 90pxThe full-width strip at the top of desktop pages. First thing seen, so viewability is excellent. Its shape suits a short message and one button — think of it as a shopfront sign, not a brochure.
MPU (Medium Rectangle)
300 × 250pxThe workhorse. Sits inside or beside content on desktop and mobile alike, which is why it usually has the deepest demand of any size. If you only create one banner, make it this one.
Half Page
300 × 600pxA tall unit that stays on screen as the reader scrolls, so it earns strong engagement. Room for a proper visual. Publishers: one of these is worth two cluttered MPUs.
Mobile Banner
320 × 50pxThe thin strip on phones. Tiny canvas — a few words and a button, nothing more. Cheap per thousand, and mobile is most UK traffic, so it earns its place despite modest click rates.
Billboard
970 × 250pxThe big desktop statement, usually top of page on content sites. Premium feel, premium price. Best for brand campaigns rather than direct response.
Square
250 × 250pxA compact unit for sidebars and tight layouts. Less common, but handy for publishers whose design cannot take an MPU.
Which should you actually use?
Advertisers: start with the MPU — it reaches the most inventory — then add a leaderboard and a mobile banner to cover desktop and phone placements properly. Keep the message identical across sizes.
Publishers: fewer, better-placed slots beat many crammed ones — both for what advertisers will pay and for your readers' patience. One leaderboard plus one in-content MPU is a sensible start; add a half page in the sidebar if your layout has one.
On dijitul ads you don't strictly need image files at all — the ad builder generates your banner in any of these sizes from a headline and a button, and it can match the design of the site it appears on.