Here are the most commonly used web banner ad sizes (IAB Standard) along with their typical names and primary use cases:

Size (px) Name Typical Placement
300 × 250 Medium Rectangle In-content, sidebars
728 × 90 Leaderboard Top of page, above header
160 × 600 Wide Skyscraper Sidebar, right-rail
320 × 50 Mobile Leaderboard Mobile screens, often sticky
300 × 600 Half-Page (Wide Skyscraper) Sidebar, high-impact units
970 × 250 Billboard Above the fold on large screens
970 × 90 Large Leaderboard Above header or between content
468 × 60 Banner Legacy placement, header
250 × 250 Square Sidebar, in-content
200 × 200 Small Square Sidebar, footer

Notes & Variations

  • Double-pixel (“Retina”) versions: To ensure crisp appearance on high-DPI screens, it’s common to serve 2× versions (e.g. 600 × 500 for a 300 × 250 ad).

  • Mobile-only sizes: Besides 320 × 50, you’ll also see 300 × 50 and 300 × 100 for in-app and mobile web.

  • High-impact “rich” units: Larger billboard (970 × 250) and half-page (300 × 600) units command higher CPMs due to their size and visibility.

These sizes cover the vast majority of placements across desktop and mobile. When planning a campaign, pick 2–3 core sizes (e.g., 300 × 250, 728 × 90, 160 × 600) and include their mobile variants to maximize fill rates and reach.