Primary Ad Unit Orientation: Landscape vs. Portrait DOOH

Primary ad unit orientation is the aspect ratio of a Digital Out-of-Home (DOOH) ad unit (landscape or portrait). It determines which screens that creative is eligible to run on. A landscape asset can’t serve on a portrait-only screen, and vice versa, so orientation isn’t only a design detail. It’s one of the first filters that determines how much of the available DOOH marketplace a creative asset can realistically reach.

Primary Ad Unit vs. Primary Ad Unit Orientation vs. Companion Ad Unit Orientation

Three related DOOH terms get confused often enough to be worth separating, because each answers a different question about the same screen:

• The primary ad unit indicates whether the main creative occupies the full screen or a partial screen.
• The primary ad unit orientation defines the aspect ratio of the main creative: landscape or portrait.
• Companion ad unit orientation describes the aspect ratio (landscape or portrait) of a secondary ad unit that runs alongside the primary one. It usually appears on its own screen or panel with its own separate spec sheet.

All three terms may appear together on the same spec sheet or RFP, which is why they get confused. The most common mistake is building the companion asset using the primary unit’s dimensions instead of its own. This leads to an improperly sized file that gets rejected or appears distorted on screen.

Standard DOOH Orientation Specs

Across most DOOH inventory, orientation aligns with a few standard aspect ratios and resolutions:

Orientation	Aspect Ratio	Common Resolution	Typical Screen Types
Landscape	16:9	1920×1080	Roadside billboards, transit shelters, office and retail displays
Portrait	9:16	1080×1920	Mall pillars, elevator screens, transit platform displays

These figures are consistent with industry-wide DOOH specification guidance, though individual screen networks and non-standard formats can vary.

Why Orientation Determines Which Inventory You Can Buy

Orientation isn’t just a creative constraint; it’s a bidding constraint. When a DOOH screen sends a bid request, it reports its orientation as part of the screen’s metadata, alongside location and size. Demand-side platforms and screen networks use that metadata to match incoming creative to eligible avails. So a campaign built only in landscape is invisible to every portrait screen in the marketplace, not only poorly suited to it. The impact on reach and efficiency is financial, not just cosmetic: providing only one orientation automatically limits the available DOOH inventory your budget can buy.

How Perion Handles Multi-Orientation DOOH Creative

Rather than requiring manual builds for each layout, Perion leverages Dynamic VAST delivery to automatically format and serve DOOH creative based on location, audience, and display specs. 

Advertisers don’t need DOOH-specific assets to start a campaign. Perion’s creative team can reformat existing creative across the thousands of screen sizes and orientations in market.  This is also the mechanism behind Perion’s broader Adaptive Creative capability and the dynamic creative optimization approach used across Perion’s programmatic DOOH campaigns.