Designing a successful digital advertising campaign starts with getting the canvas right. If your banner dimensions are even slightly off, publishers will reject your creatives, or worse, ad networks will automatically crop, stretch, or blur your artwork, killing your click-through rates (CTR).
Whether you are designing for Google Display Network (GDN), social media, or high-impact programmatic placements, here is your definitive, complete guide to web banner sizes in 2026.
1. The Industry Standard Sizes (The IAB Core Four)
The Interactive Advertising Bureau (IAB) establishes universal standards to ensure ads can run seamlessly across thousands of publisher websites. If you are building a standard display campaign, focusing on these four core sizes covers the vast majority of desktop and mobile inventory:
- Medium Rectangle (300 × 250 px): The undisputed king of display advertising. It fits snugly within sidebar columns or natively inside text content, boasting the highest inventory volume across the web.
- Leaderboard (728 × 90 px): Traditionally placed at the very top of a website header. While still widely used, it has largely been complemented by larger billboard sizes on modern desktop displays.
- Large Rectangle (336 × 280 px): Slightly larger than the standard medium rectangle, this format yields slightly higher engagement rates and is favored by many premium publishers.
- Half Page / Large Skyscraper (300 × 600 px): A high-impact vertical format that commands attention. Because of its generous real estate, it is heavily favored for storytelling and brand-building campaigns.
2. High-Performing Mobile Banner Sizes
With mobile traffic continuing to dominate global web usage, optimizing for smaller screens is non-negotiable. Designing separate mobile assets prevents your text from becoming illegible.
- Mobile Leaderboard (320 × 50 px): The standard banner size for mobile web browsers and app banners, usually pinned to the bottom or top of a smartphone screen.
- Large Mobile Banner (320 × 100 px): Offering double the height of the standard mobile leaderboard, this format provides much better breathing room for branding and a clearer call-to-action (CTA).
- Mobile Medium Rectangle (300 × 250 px): Just like on desktop, this versatile box seamlessly transitions into mobile articles and responsive layouts.
3. Desktop & High-Impact Formats
For brands looking to make a splash on large desktop monitors, high-impact display units deliver maximum visual weight:
- Billboard (970 × 250 px): A massive horizontal banner usually positioned right below the site navigation. It delivers incredible brand visibility for major product launches.
- Half Page (300 × 600 px): As mentioned above, its vertical dominance allows creative teams to stack headlines, imagery, and bold CTA buttons effectively.
Quick-Reference Comparison Table
| Format Name | Dimensions (Width × Height) | Primary Placement | Device Type |
| :— | :— | :— | :— |
| Medium Rectangle | 300 × 250 px | Sidebar / In-content | Desktop & Mobile |
| Leaderboard | 728 × 90 px | Header / Footer | Desktop |
| Half Page | 300 × 600 px | Sidebar (High-impact) | Desktop |
| Mobile Leaderboard | 320 × 50 px | Top / Bottom of screen | Mobile |
| Large Mobile Banner | 320 × 100 px | Top / Bottom of screen | Mobile |
| Billboard | 970 × 250 px | Top of page (Hero) | Desktop |
Best Practices for Banner Design Success
Knowing the dimensions is only half the battle. To turn pixels into conversions, keep these rules of thumb in mind:
- Keep File Sizes Lean: Ad networks enforce strict file weight limits (often under 150KB for standard HTML5/image ads) to ensure pages load instantly. Compress your assets without sacrificing clarity.
- Establish a Visual Hierarchy: Lead with a strong hook or value proposition, support it with a clean product visual or graphic, and anchor it with a contrasting, clickable CTA button (
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