The Anatomy of a High-Converting Campaign: The Definitive Guide to LinkedIn Paid Ad Specs

Running campaigns on LinkedIn offers an unmatched advantage for B2B marketers: direct access to decision-makers by job title, industry, and seniority. However, even the most brilliant targeting strategy will fall flat if your creative assets are rejected by Campaign Manager or mangled by mobile auto-truncation.

Technical precision is half the battle in paid social. This guide breaks down the exact dimensions, file formats, and text limits for LinkedIn’s primary ad formats so you can design with confidence from day one.

1. Single Image Ads (The Feed Workhorse)

Single image sponsored content appears directly in the professional feed on both desktop and mobile. Because it is your most versatile format, getting the aspect ratio right prevents awkward white bars or unexpected clipping.

• Landscape (1.91:1): Recommended size is 1200 × 628 px (Min: 640 × 360 px). Delivers across desktop and mobile.
• Square (1:1): Recommended size is 1200 × 1200 px (Min: 360 × 360 px). Great for cross-platform visual gravity.
• Vertical (4:5): Recommended size is 720 × 900 px (Min: 360 × 450 px). Maximizes screen estate on mobile feeds.
• File Requirements: JPG, PNG, or static GIF up to 5 MB.

Text & Copy Caps:

• Introductory Text: Up to 600 characters, but keep it under 150 characters to avoid truncation behind a “See more” link.
• Headline: Up to 200 characters, though the first 70 characters carry the visual weight before mobile cutoff.

2. Video Ads

Video is a powerful medium for brand awareness and product walkthroughs, but high friction during upload can derail production timelines.

• Aspect Ratios: 16:9 (Landscape), 1:1 (Square), 4:5 (Vertical), and 9:16 (Vertical).
• Resolution Guidelines: Up to 1920 × 1080 px for landscape; up to 1080 × 1920 px for vertical.
• File Format & Size: MP4 format, ranging from 75 KB to 500 MB.
• Duration: From 3 seconds up to 30 minutes (though 15 to 30 seconds typically yields the strongest completion rates for direct-response goals).

3. Carousel Ads

Carousels let you tell a sequential story, showcase a product suite, or break down a step-by-step framework across multiple swipeable cards.

• Card Dimensions: Exactly 1080 × 1080 px (1:1 square ratio).
• Card Count: 2 to 10 cards per ad.
• File Specifications: JPG, PNG, or non-animated GIF, max 10 MB per card.
• Text Limits:
  • Introductory Text: 255 characters max.
  • Card Headline: 45 characters max per card (keep it punchy so it doesn’t wrap awkwardly).

4. Document Ads

If your strategy relies on thought leadership whitepapers, research reports, or deep-dive slide decks, Document Ads allow users to preview and read PDFs directly in-feed without navigating away.

• File Types: PDF, PPT, PPTX, DOC, or DOCX.
• Maximum File Size: Up to 100 MB (and up to 300 pages).
• Design Tip: LinkedIn displays the initial pages (often up to the first 10 pages) right in the feed. Use large typography (18pt+) and clean visuals because small desktop text shrinks dramatically on mobile screens.

5. Message, Conversation, and Dynamic Ads

For targeted account-based marketing (ABM) or direct lead generation, LinkedIn offers messaging and right-rail dynamic formats.

• Spotlight Ads (Dynamic): Feature a 100 × 100 px company logo, a headline (50 characters), description (70 characters), company name (25 characters), and an optional 300 × 250 px custom background image (max 2 MB).
• Text Ads: Right-rail units featuring a 100 × 100 px logo, a 25-character headline, and a 75-character description.
• Conversation/Message Ads: Include a sender persona, a subject line (up to 60 characters), message text (up to 1,500 characters), CTA buttons (up to 20 characters), and an optional desktop companion banner sized at 300 × 250 px (JPG/PNG, max 2 MB).

Quick-Reference Specification Matrix

| Format | Recommended Dimensions | Max File Size | Key Copy Constraints |
| :— | :— | :— | :— |
| Single Image (Square) | 1200 × 1200 px | 5 MB | Headline: ~70 chars visible |
| Single Image (Landscape) | 1200 × 627 px | 5 MB | Intro Text: ~150 chars visible |
| Video Ad | 1920 × 1080 px (16:9) | 500 MB | 3s to 30 min duration |
| Carousel Card | 1080 × 1080 px | 10 MB per card | Card Headline: 45 chars max |
| Document Ad | Standard PDF/PPT layout | 100 MB | Up to 300 pages |
| Spotlight Ad | 100 × 100 px logo | 2 MB | Headline: 50 chars / Desc: 70 chars |

Final Checklist Before Launch

Before you push your creative assets live into Campaign Manager, verify that your text front-loads your core value proposition within the first two lines, ensure your images strictly adhere to the supported color space (RGB), and test your landing page links with UTM tracking parameters. Clean technical execution ensures your budget goes toward engaging prospects rather than troubleshooting format errors.