The Definitive Guide to LinkedIn Ad Sizes: Stop Guessing and Start Converting

Let’s face it: nothing kills the momentum of a high-performing B2B marketing campaign faster than getting an automated rejection email from LinkedIn Campaign Manager because your asset dimensions are off by a few pixels.

Worse yet is when your ad does get approved, but it looks pixelated, gets awkwardly cropped on mobile devices, or forces key text to hide beneath a clumsy interface overlay.

In B2B advertising, your creative is a proxy for your brand’s professionalism. If your design isn’t optimized for LinkedIn’s strict technical parameters, decision-makers will scroll right past you. This guide cuts through the noise, giving you the exact, up-to-date dimensions, file limits, and strategic best practices for every major LinkedIn ad format.

1. Single Image Ads (Sponsored Content)

Single image ads are the backbone of LinkedIn advertising. They sit right in the professional feed, making them ideal for brand awareness, lead generation, and driving traffic to whitepapers or webinars.

While LinkedIn supports a few different aspect ratios, choosing the right one dictates how much screen real estate you command.

• Square (Recommended Default): $1200 times 1200$ pixels | Aspect Ratio: $1:1$
  • Why use it: It’s the safest all-around bet. It looks great on desktop and commands solid visual authority on mobile feeds without getting clipped.
• Vertical: $1200 times 1500$ pixels | Aspect Ratio: $4:5$
  • Why use it: Maximum mobile feed dominance. If your target audience is almost exclusively scrolling on phones, this format forces them to engage with your creative longer.
• Horizontal (Landscape): $1200 times 627$ pixels | Aspect Ratio: $1.91:1$
  • Why use it: Traditional format that works well for desktop-heavy enterprise campaigns, though it takes up less vertical space on mobile.

Technical Specs:

• File Types: JPG, PNG, or GIF (avoid heavy animated GIFs; static graphics usually convert better in professional contexts).
• Max File Size: 5 MB
• Copy Limits: Introductory text (150 characters recommended), Headline (70 characters).

2. Carousel Ads

Carousels are your go-to format when a single image isn’t enough to tell a complete story. They are phenomenal for multi-step frameworks, product feature breakdowns, or summarizing complex research reports.

• Card Dimensions: $1080 times 1080$ pixels (strict $1:1$ square ratio)
• Card Count: 2 to 10 cards per ad

💡 Design Pro-Tip: On mobile devices, users typically see about 1.5 cards at a time. Design your first card to create a strong curiosity gap that explicitly prompts a swipe. Also, leave a safety margin at the bottom of each card, as headline text overlays can occasionally clip tight layouts.

Technical Specs:

• File Types: JPG or PNG (No GIFs)
• Max File Size: 10 MB per card
• Copy Limits: Card headline (45 characters), Intro text (255 characters).

3. Video Ads

Video is unmatched for building emotional connection and explaining intricate SaaS products or services. LinkedIn supports multiple orientations depending on where your audience is watching.

• Square: $1080 times 1080$ pixels ($1:1$) — Great for talking-head clips and social animations.
• Vertical: $1080 times 1350$ pixels ($4:5$) — The gold standard for mobile-first video strategies.
• Landscape: $1920 times 1080$ pixels ($16:9$) — Ideal if you are repurposing webinars or high-production product demos.

Technical Specs:

• File Format: MP4
• Max File Size: Up to 5 GB
• Duration: 3 seconds to 30 minutes (though 15 to 30 seconds yields the highest completion rates for cold traffic).
• Thumbnails: Always upload a custom thumbnail (JPG/PNG, matching the video’s aspect ratio, under 2 MB) rather than letting LinkedIn auto-generate a blurry freeze-frame.

4. Document Ads

If your primary lead magnet is an e-book, proprietary report, or deep-dive playbook, Document Ads allow users to scroll through your PDF right inside the LinkedIn feed without navigating to an external landing page.

• Recommended Page Size: Standard Letter ($8.5 times 11$ inches) or A4, formatted in portrait or landscape.
• Max File Size: 100 MB
• Page Limit: Up to 300 pages (though 5 to 10 pages is the sweet spot for keeping attention).
• Accepted Formats: PDF, DOC, DOCX, PPT, PPTX.

5. Sidebar & Auxiliary Formats (Text & Spotlight Ads)

While the feed commands the lion’s share of attention, desktop right-rail placements are cost-effective tools for retargeting and steady brand reinforcement.

• Text Ads: Utilize a tiny $100 times 100$ pixel logo coupled with a tight headline (25 characters) and description (75 characters). They are small, text-heavy units that live on the right-hand side of desktop screens.
• Spotlight Ads: Personalized dynamic ads that feature a $100 times 100$ pixel company logo alongside an optional $300 times 250$ pixel custom background image.

Quick-Reference LinkedIn Ad Size Cheat Sheet

| Ad Format | Recommended Dimensions | Aspect Ratio | Max File Size | File Formats |
| :— | :— | :— | :— | :— |
| Single Image (Square) | $1200 times 1200$ px | $1:1$ | 5 MB | JPG, PNG, GIF |
| Single Image (Vertical) | $1200 times 1500$ px | $4:5$ | 5 MB | JPG, PNG, GIF |
| Single Image (Landscape)| $1200 times 627$ px | $1.91:1$ | 5 MB | JPG, PNG, GIF |
| Carousel Card | $1080 times 1080$ px | $1:1$ | 10 MB | JPG, PNG |
| Video (Vertical) | $1080 times 1350$ px | $4:5$ | 5 GB | MP4 |
| Video (Landscape) | $1920 times 1080$ px | $16:9$ | 5 GB | MP4 |
| Text Ad Logo | $100 times 100$ px | $1:1$ | 2 MB | JPG, PNG |

Final Quality Control Checklist Before Launch

Before you hit publish on your next campaign, run your assets through this final verification protocol:

1. The Safe Zone Check: Keep important text, logos, and product mockups centered. Avoid placing critical data within 50 pixels of the bottom edges where platform UI elements (like CTAs and user profile tags) overlay the graphic.
2. File Compression: Ensure your file sizes are well under the ceiling limits to prevent loading lag on slower mobile networks, without sacrificing image clarity.
3. The Mobile Preview Test: Always use LinkedIn’s native preview tool to view your ad layout on a mobile screen format before approving spend.

By respecting these dimensions, you ensure your creative stands tall in the feed, projecting the high-caliber polish your B2B brand demands.