Authored and reviewed by the Bannerninjas team ·
Fixed-size display banners occupy a slot measured in pixels: width first, height second. A publisher’s available inventory determines the useful sizes. A size appearing in a common industry guide does not guarantee placement availability.
Start with the media plan
300×250 (MPU) is a compact rectangular unit. 300×600 (DMPU or half page) provides a taller storytelling area. 970×250 (Billboard) is a wide high-impact unit, while 728×90 (Leaderboard) is a shallow horizontal placement. IAB UK describes these common fixed formats; your publisher decides which slots it offers.
Our UAP and UK Core 5 sets
Bannerninjas uses UAP as its own three-size package label: 300×250, 300×600 and 970×250. It is not a claim that this exact set is a universal current IAB or Google standard. UK Core 5 adds 728×90 and 320×50. Display 6 adds 160×600.
Mobile is not one size
320×50 is a shallow mobile banner; 320×100 gives more vertical space. The MPU also appears on mobile inventory. Keep copy legible and prioritise a single message. Ask the buyer whether fixed HTML5, static images or responsive assets are wanted.
Responsive ads are a different deliverable
Google responsive display ads combine image and text assets into multiple layouts. Their aspect-ratio requirements are not HTML5 slot dimensions. Do not order a fixed-size ZIP as a substitute without checking the campaign type.
Build a useful size shortlist
Ask the media buyer for the booked placement list, not just a preferred visual. Record the exact width and height, desktop or mobile inventory, platform and expected fallback for each placement. Compare that list with UAP, UK Core 5 and Display 6 before ordering. Avoid adding a size solely because it is familiar: if the campaign will not use it, producing it adds scope without a confirmed destination. A custom size can be selected separately in the configurator.
Plan the message across aspect ratios
A 300×600 layout can support a sequence that does not fit comfortably into 320×50. Decide which element must remain visible in every output: usually the brand, one proposition and one clear CTA. Treat each layout as an adaptation, rather than shrinking the largest design. Check that mandatory qualifications remain readable, logos retain their proportions and the final frame communicates the offer even when the viewer misses the opening animation.
Fixed dimensions do not settle technical acceptance
A 970×250 booking can still have publisher-specific animation, weight or click requirements. Ask whether high-density artwork is permitted and whether the delivered HTML5 canvas must remain at the booked CSS dimensions. The platform documentation linked below is the starting point; the buyer should confirm any placement exceptions. Keep the approved specifications with the later project brief so the production team is not choosing requirements from assumptions.
Confirm the target account, campaign type and publisher’s current requirements before production. Specifications and HTML5 upload access vary.