The Half Page Ad Explained
The 300x600 half page ad, sometimes called the half-page unit or large skyscraper, is one of the IAB's Rising Stars ad formats. It offers 180,000 square pixels of creative space, which is more than double the 75,000 pixels available in a 300x250 medium rectangle. This generous canvas makes it the preferred format for brand awareness campaigns that need visual impact, storytelling capability, and room for interactive elements. The half page is classified as a premium ad unit, and publishers typically charge higher CPMs for it compared to standard display formats.
Sidebar Placement and Layout Requirements
The 300x600 is almost exclusively a sidebar ad format. It requires a sidebar that is at least 320 pixels wide and a content area tall enough to display the full 600-pixel height without pushing below the fold excessively. On pages with shorter content, the half page ad may extend beyond the article, creating visual imbalance. Best practice is to reserve this unit for long-form content pages such as articles, guides, and product reviews where the page height comfortably exceeds 1000 pixels. Some publishers implement sticky positioning so the ad remains visible as users scroll through the content, significantly boosting viewability metrics.
Rich Media and Interactive Opportunities
The large vertical canvas of the half page unit makes it ideal for rich media creatives. Common implementations include expandable units that grow to fill more of the screen on hover, video ads with an integrated player, product carousels that users can swipe through, and interactive mini-experiences. HTML5 creatives should keep the initial load under 200KB and total assets under 2MB per IAB guidelines. When building interactive elements, ensure all clickable areas are clearly indicated and that the ad does not auto-play audio, which violates Better Ads Standards and most publisher policies.
Viewability and Performance Optimization
Due to its 600-pixel height, the half page ad often faces viewability challenges since the entire creative may not be visible in the viewport simultaneously. The IAB viewability standard for display ads requires 50% of the ad to be in view for at least one continuous second. For the 300x600, this means at least 300 pixels of height must be visible. Design your creative so the most important elements, including the brand logo, key message, and call-to-action, appear in the top 300 pixels of the unit. This ensures maximum impact even when only the upper half is in the viewport. Publishers should also consider lazy loading the ad to avoid counting impressions that are never seen.