Mastering LinkedIn Ad Sizes: The Ultimate Guide for High-Converting Campaigns

When it comes to B2B marketing, LinkedIn is the undisputed heavyweight champion. With over a billion professionals networking, sharing industry insights, and searching for solutions, it is a goldmine for decision-makers and lead generation.

However, even the most compelling copy and precise audience targeting will fall flat if your creative assets look blurry, get awkwardly cropped, or fail to catch the eye as users endlessly scroll their feeds. Adopting the correct specifications is the difference between a high-performing campaign and wasted ad spend.

This comprehensive guide breaks down everything you need to know about LinkedIn ad sizes, formats, and best practices to ensure your brand always puts its best pixel forward.

Why LinkedIn Ad Sizes Matter

Before diving into the numbers, it’s worth asking: Why does exact sizing matter so much?

1. User Experience: Professionals use LinkedIn across desktop browsers, mobile apps, and tablets. Properly sized ads ensure your message renders cleanly and legibly across all devices.
2. Professionalism: Pixelated, stretched, or cut-off images signal a lack of attention to detail—the last thing you want when trying to build trust with B2B clients.
3. Delivery and Performance: Platforms optimize for assets that fit their native containers. Ad formats that violate aspect ratios can get penalized with lower visibility or higher costs.

1. Single Image Ads (Sponsored Content)

Single image ads are the backbone of most LinkedIn campaigns. They appear directly in the user’s feed alongside organic posts, making them feel native and unobtrusive.

• Landscape (Most Common):
  • Recommended Size: 1200 x 627 pixels
  • Aspect Ratio: 1.91:1
• Square:
  • Recommended Size: 1080 x 1080 pixels
  • Aspect Ratio: 1:1
• Vertical (Mobile-Optimized):
  • Recommended Size: 1080 x 1350 pixels
  • Aspect Ratio: 4:5
• File Formats: JPG or PNG
• Maximum File Size: 5 MB

Pro Tip: Vertical ads take up more physical space on mobile screens, making them exceptional for stopping the scroll. However, ensure critical text and imagery stay centered so they don’t get obscured by UI overlays.

2. Carousel Image Ads

Carousels allow you to tell a sequential story, showcase a product line up, or break down a complex multi-step process using multiple swipeable cards.

• Card Image Size: 1080 x 1080 pixels
• Aspect Ratio: 1:1
• Number of Cards: 2 to 10 cards per carousel
• File Formats: JPG or PNG
• Maximum File Size: 10 MB per card
• Text Limits: Introductory text up to 255 characters; headline per card up to 45 characters (for destination URLs) or 30 characters (for Lead Gen Forms).

3. Video Ads

Video is one of the most engaging ways to build brand affinity, explain a product feature, or share customer testimonials on LinkedIn.

• Landscape:
  • Recommended Size: 1920 x 1080 pixels (16:9 ratio)
• Square:
  • Recommended Size: 1080 x 1080 pixels (1:1 ratio)
• Vertical:
  • Recommended Size: 1080 x 1350 pixels (4:5 ratio) or 1080 x 1920 pixels (9:16 ratio)
• Length: 3 seconds to 30 minutes (though 15–30 seconds typically yields the highest completion rates for top-of-funnel campaigns).
• File Format: MP4
• Frame Rate: 30 fps or lower
• Max File Size: 200 MB

Pro Tip: Over 80% of LinkedIn videos are watched on mobile devices with the sound off. Always bake open captions or dynamic subtitles directly into your video files!

4. Thought Leader Ads

Thought Leader Ads allow you to amplify organic posts published by your company’s executives, founders, or employees. They leverage the authenticity of personal profiles while utilizing the targeting power of Campaign Manager.

Because these build on organic posts, the sizes depend on what the creator originally posted:

• Images: Follow standard single image guidelines (1200 x 627 or 1080 x 1080 pixels).
• Videos: Standard landscape or square ratios apply.
• Text: Keep the hook strong in the first 150 characters before LinkedIn truncates the preview with a “see more” link.

5. Text Ads & Spotlight Ads (Dynamic Ads)

Dynamic ads personalize themselves using the target user’s profile data (such as their first name, company name, or job title) and live on the right-hand rail of the LinkedIn desktop interface.

• Spotlight Ads:
  • Custom Company Logo Size: 100 x 100 pixels (PNG or JPG)
  • Background Image (Optional): 300 x 250 pixels
• Text Ads:
  • Image Size (Optional): 100 x 100 pixels
  • Headline: Up to 25 characters
  • Description: Up to 75 characters

6. Message Ads & Conversation Ads

Delivered straight to a user’s LinkedIn Messaging (InMail) inbox, these ads facilitate a direct, conversational line to your prospective leads.

• Custom Banner Image (Companion Image for Desktop):
  • Recommended Size: 300 x 250 pixels
  • File Formats: JPG, GIF (non-animated), or PNG
  • Max File Size: 2 MB

Best Practices for Designing LinkedIn Ads

1. Design for Mobile First: Over 60% of LinkedIn traffic originates from mobile devices. If your text is too small to read on a smartphone screen, you are losing conversions.
2. Contrast and Color: Stand out against LinkedIn’s signature white and professional blue interface by using high-contrast color palettes and bold visual anchors.
3. Prioritize the “Hook”: Whether it’s the first three seconds of a video or the upper third of an image, place your core value proposition immediately where the eye lands.
4. Test Multiple Ratios: Don’t just rely on landscape formats. Run A/B tests pitting square (1:1) and vertical (4:5) formats against traditional landscape creatives to see what resonates best with your specific audience.

By aligning your design workflow with these exact dimensions, you’ll ensure crisp visual execution, protect your brand image, and maximize the ROI of your next LinkedIn campaign.