Master LinkedIn Paid Ad Specs: The Ultimate Reference Guide

Running successful B2B campaigns on LinkedIn requires more than just a compelling value proposition and precise audience targeting—it demands technical execution. Uploading an asset with the wrong pixel dimensions or exceeding strict character limits can result in awkward cropping, low-quality compression, or outright ad rejection by LinkedIn’s review system.

To help creative and media teams align seamlessly, this guide breaks down the essential technical and copy specifications for LinkedIn’s core paid ad formats.

1. Sponsored Content (Feed Formats)

Sponsored Content appears directly in the LinkedIn feeds of your target audience, making it the most heavily utilized tool for brand awareness, thought leadership, and lead generation.

Single Image Ads

Single image ads are versatile workhorses, ideal for driving website traffic or capturing leads via built-in Lead Gen Forms.

• Aspect Ratios & Dimensions:
  • Landscape (1.91:1): 1200 × 628 pixels recommended (Min: 640 × 360 px)
  • Square (1:1): 1200 × 1200 pixels recommended (Min: 360 × 360 px)
  • Vertical (4:5): 720 × 900 pixels recommended to avoid empty margins on mobile feeds
• File Formats: JPG, PNG, or non-animated GIF
• Max File Size: 5 MB
• Introductory Text: 150 characters recommended to avoid truncation on mobile devices (600 characters max)
• Headline: 70 characters recommended before truncation (200 characters max)

Video Ads

Video is unmatched for demonstrating product value, sharing customer testimonials, or delivering high-impact brand messages.

• Aspect Ratios & Dimensions:
  • Landscape (16:9): 1920 × 1080 px
  • Square (1:1): 1920 × 1920 px (Max)
  • Vertical (4:5 / 9:16): 1080 × 1350 px or 1080 × 1920 px
• File Format: MP4
• File Size: 75 KB to 500 MB
• Duration: 3 seconds to 30 minutes (shorter cuts between 15–30 seconds consistently yield higher engagement)
• Frame Rate: 30 FPS or lower

Carousel Ads

Carousels allow you to display a scrollable sequence of 2 to 10 cards, perfect for deep-diving into product features, breaking down sequential data, or telling a multi-part brand story.

• Card Count: 2 to 10 cards
• Image Size: 1080 × 1080 pixels (1:1 aspect ratio)
• File Formats & Size: JPG or PNG; maximum 10 MB per card
• Card Headline: 45 characters maximum
• Introductory Text: Up to 150 characters recommended (255 characters max)

Document Ads

Document ads let users read and interact with deep-dive assets—like whitepapers, reports, or case studies—directly within their LinkedIn feed without navigating to an external landing page.

• Supported File Types: PDF, DOC, DOCX, PPT, PPTX
• Max File Size: 100 MB
• Page Limit: Up to 300 pages (shorter guides between 10 to 20 pages typically see higher completion rates)

2. Sponsored Messaging (Direct Inmail)

Sponsored Messaging delivers targeted messages directly into a professional’s LinkedIn messaging inbox.

Message & Conversation Ads

• Message Text: Up to 1,500 characters for standard Message Ads; up to 8,000 characters for Conversation Ads
• Subject Line: 60 characters max (Message Ads only)
• Call-to-Action (CTA) Button: 20 characters max
• Custom Footer / Terms: Up to 20,000 characters (optional)
• Desktop Companion Banner (Optional): 300 × 250 pixels (JPG or PNG, max 2 MB)

3. Right-Rail & Discovery Formats

These compact placements are built for steady, low-friction visibility on desktop views.

Text Ads

Text ads sit discreetly on the right-hand side of the desktop feed and operate on a cost-per-click (CPC) or cost-per-impression (CPM) model.

• Logo Image: 100 × 100 pixels (JPG or PNG, max 2 MB)
• Headline: 25 characters max
• Description: 75 characters max

Spotlight & Follower Ads

Dynamic ads personalize content dynamically using the viewer’s profile data (such as their profile picture or job title) to drive page followers or website conversions.

• Company Logo: 100 × 100 pixels (JPG or PNG, max 2 MB)
• Optional Background Image (Spotlight Ads): 300 × 250 pixels (max 2 MB)
• Headline: 50 characters max
• Description: 70 characters max
• CTA Button Text: 18 characters max

Quick Reference Summary Table

| Format | Primary Asset Type | Optimal Dimension / Ratio | Max File Size | Key Copy Limit |
| :— | :— | :— | :— | :— |
| Single Image | Image | 1200 × 1200 px (1:1) | 5 MB | 150 chars (Intro) |
| Video | MP4 Video | 1920 × 1080 px (16:9) | 500 MB | 150 chars (Intro) |
| Carousel | Multiple Images | 1080 × 1080 px per card | 10 MB per card | 45 chars (Card Headline) |
| Document | PDF / Presentation | N/A (Standard doc layouts) | 100 MB | 70 chars (Headline) |
| Text Ad | Logo + Text | 100 × 100 px | 2 MB | 25 chars (Headline) |

Best Practices for Campaign Launch

1. Front-Load Your Copy: Because LinkedIn truncates mobile introductory text past approximately 150 characters, place your core hook and value proposition immediately.
2. Design for Sound-Off Viewing: Most professionals browse LinkedIn on mute. Always embed open captions or synchronized subtitles into your video assets.
3. Audit Before Publishing: Always preview your ads using LinkedIn’s campaign manager preview tool across both desktop and mobile layouts to catch text clipping before your budget goes live.