LinkedIn Ads Sizes Guide: Complete Specification & Design Checklist for 2026

Navigating the specifications for LinkedIn advertising can make or break a B2B campaign. Because LinkedIn is a professional network where trust, clarity, and authority drive conversions, your creative assets must look sharp, professional, and optimized for both desktop feeds and mobile screens.

Whether you are launching a thought leadership campaign, sponsoring a newsletter, or driving enterprise software leads, this comprehensive guide covers every active LinkedIn ad size, format specification, and best practice.

1. Single Image Ads

The workhorse of LinkedIn advertising. Single image ads appear natively in the user feed and are versatile enough for brand awareness, lead generation, and content promotion.

• File Formats: JPG, PNG (non-animated)
• Maximum File Size: 5 MB
• Aspect Ratio & Recommended Dimensions:
  • Landscape (1.91:1): 1200 x 627 pixels (Most common for website link cards)
  • Square (1:1): 1080 x 1080 pixels (Highly recommended for high feed visibility)
  • Vertical (9:16): 1080 x 1920 pixels (Optimized for mobile-first scrolling)
• Text Specs:
  • Introductory Text: Up to 150 characters recommended (truncates around 220 characters).
  • Headline: Up to 70 characters recommended (truncates around 200 characters).
  • Description: Up to 70 characters (optional, only appears on certain layouts).

2. Carousel Image Ads

Carousels allow you to tell a visual story, showcase a product feature lineup, or break down a complex B2B framework across multiple swipeable cards.

• Number of Cards: 2 to 10 cards per ad
• File Formats: JPG, PNG
• Maximum File Size: 10 MB per card
• Card Specifications:
  • Aspect Ratio: 1:1 exactly
  • Recommended Resolution: 1080 x 1080 pixels
• Text Specs:
  • Introductory Text: Up to 150 characters recommended.
  • Card Headline: Up to 45 characters (if linking to a landing page) or 30 characters (if linking to a Lead Gen Form).

3. Video Ads

Video is essential for humanizing your brand, demonstrating software workflows, or showcasing customer testimonials.

• File Format: MP4
• File Size: 75 KB to 200 MB
• Duration: 3 seconds to 30 minutes (though 15 to 30 seconds typically yields the highest completion rates for top-of-funnel awareness).
• Aspect Ratios & Resolutions:
  • Landscape (16:9): 1920 x 1080 (Desktop & mobile)
  • Square (1:1): 1080 x 1080
  • Vertical (9:16 or 4:5): 1080 x 1920 or 1080 x 1350 (Strongly recommended for mobile feed engagement)
• Captions: Highly recommended to upload a separate SRT file, as many professionals watch feed videos with the sound off by default.

4. Thought Leadership & Document Ads

Document ads allow users to read PDFs (like whitepapers, checklists, or industry reports) directly inside the LinkedIn feed without clicking away to an external landing page.

• File Formats: PDF, DOC, DOCX
• Page Count: Up to 300 pages (recommended: 5–15 pages for digestible snackable content).
• Maximum File Size: 100 MB
• Orientation: Vertical or Horizontal (Standard portrait ratios like A4 or Letter work best).
• Text Specs:
  • Introductory Text: Up to 150 characters recommended.
  • Document Title: Up to 60 characters.

5. Event Ads

Promoting a virtual webinar, hybrid conference, or local meetup? Event ads pull details directly from your LinkedIn Event page.

• Image Dimensions: 1200 x 628 pixels (1.91:1 aspect ratio)
• File Formats: JPG, PNG
• Max File Size: 5 MB
• Text Specs:
  • Introductory Text: Up to 150 characters.
  • Event Title & Date/Time: Pulled automatically from the host event page.

6. Message Ads & Conversation Ads

Delivered directly to a target professional’s LinkedIn Messaging (InMail) inbox when they are active on the platform.

• Banner Companion Ad (Optional):
  • Dimensions: 300 x 250 pixels
  • Formats: JPG, GIF, PNG (Up to 40 KB)
• Text Specs:
  • Sender Name: Selected from a verified sender profile.
  • Message Subject: Up to 60 characters.
  • Message Body: Up to 1,500 characters recommended (includes rich text formatting like bolding and hyperlinks).
  • Call-to-Action (CTA) Button: Up to 20 characters per button.

Quick Design Best Practices for High ROI

1. Prioritize Square & Vertical: While horizontal (1.91:1) assets are traditional, square (1:1) and vertical (9:16) formats take up more screen real estate on mobile feeds, significantly lifting click-through rates (CTR).
2. Design for Sound-Off Viewing: Always burn captions or key callouts directly into your video files. Professionals scrolling during work breaks or meetings rarely turn audio on immediately.
3. Keep Text Clear and Legible: Avoid placing critical value propositions in the bottom 25% of image assets, where UI elements like captions, user handles, and CTA buttons overlap.
4. A/Test Multiple Formats: Combine standard single images for broad awareness with document or carousel ads for mid-funnel consideration to see which medium your specific target audience prefers.