Standard Web Banner Dimensions Guide: Sizes & Formats

The Complete Guide to Web Banner Dimensions: Sizes, Best Practices, and Formats for 2026

Digital advertising moves at a blistering pace, but one foundational element remains unchanged: banner dimensions. Whether you are launching a Google Display Network campaign, designing eye-catching social media headers, or building a high-converting website hero image, choosing the right size can mean the difference between a high click-through rate (CTR) and getting completely ignored.

Getting your dimensions wrong leads to frustrating layout shifts, distorted or blurry images, and wasted ad spend. This guide covers the most effective web banner dimensions, standard ad sizes, platform-specific requirements, and best practices to ensure your visuals always look sharp and professional.

Part 1: Standard IAB Ad Sizes (The Industry Heavyweights)

The Interactive Advertising Bureau (IAB) sets the baseline for display advertising across the web. If you are running display ads via Google Ads or programmatic networks, sticking to these standard dimensions ensures your creative fits seamlessly onto millions of publisher sites.

The following four sizes drive the vast majority of display impressions and conversions:

• Medium Rectangle ($300 times 250text{ px}$): The undisputed king of display advertising. It fits comfortably within sidebars and seamlessly integrates into inline article content on both desktop and mobile web. Best for: High availability, universal compatibility, and strong performance.
• Leaderboard ($728 times 90text{ px}$): Traditionally placed at the very top of a website header, this classic horizontal banner is a staple for desktop layouts. Best for: Brand awareness and high-visibility placements.
• Large Skyscraper ($160 times 600text{ px}$): A tall, vertical banner designed for website sidebars. It allows for more vertical storytelling and keeps your brand in view as the user scrolls. Best for: Vertical margin placements on desktop blogs and news sites.
• Half Page / Large Rectangle ($300 times 600text{ px}$): Offering double the vertical real estate of a medium rectangle, this format commands attention and provides ample space for compelling visuals and clear calls to action (CTAs). Best for: Immersive storytelling and high-impact campaigns.

Part 2: Mobile-First Web Banner Dimensions

With mobile traffic dominating global web usage, designing ads and site headers that look incredible on smaller screens is non-negotiable.

• Mobile Leaderboard ($320 times 50text{ px}$): The standard banner size for mobile web browsers. It sits neatly at the bottom or top of mobile screens without blocking core content.
• Large Mobile Banner ($320 times 100text{ px}$): A slightly taller mobile variant that doubles the vertical height of the standard mobile leaderboard, giving you more breathing room for text and buttons.
• Mobile Rectangle ($300 times 250text{ px}$): Because the standard $300 times 250$ medium rectangle scales down gracefully, it remains one of the top-performing formats across both desktop and mobile devices.

Part 3: Website Hero Banners & Header Dimensions

If you aren’t running paid ads but are designing a custom website banner (such as a hero section or promotional header), you aren’t bound by rigid IAB standards. Instead, you need to account for responsive design and varying screen widths.

Pro Tip: Modern websites use fluid layouts. Rather than designing for a single fixed pixel width, aim for aspect ratios that adapt cleanly to different screens.

• Standard Desktop Hero Banner: $1920 times 1080text{ px}$ (Full HD) or $1920 times 600text{ px}$ for a wider, shallower letterbox look.
• Safe Zone Rule: Always keep your primary text, key graphics, and CTA buttons centered within the middle $1200text{ px}$ to prevent crucial elements from getting cropped out on smaller laptop screens or tablets.
• Mobile Hero Banner: Typically designed around an aspect ratio of $1:1$ or $4:3$ (