Mastering LinkedIn Paid Ad Specs: The Ultimate Guide for B2B Marketers

LinkedIn is the undisputed heavyweight champion of B2B digital marketing. With over 1 billion members spanning decision-makers, executives, and industry professionals, it offers a precision-targeted ecosystem that other social platforms simply cannot match. However, running a successful LinkedIn advertising campaign requires strict adherence to technical specifications.

Getting your ad specs right ensures your creative assets look professional, load quickly, and never get awkwardly cropped or rejected by LinkedIn’s review process. This comprehensive guide covers the essential ad specifications for every major LinkedIn ad format, along with best practices to maximize your return on ad spend (ROAS).

1. Single Image Ads

Single image ads appear directly in the LinkedIn feed, making them one of the most versatile formats for brand awareness, lead generation, and content promotion.

• Image File Types: JPEG or PNG
• Maximum File Size: 5 MB
• Image Aspect Ratios & Dimensions:
  • Landscape (1.91:1): 1200 x 627 pixels (Recommended)
  • Square (1:1): 1080 x 1080 pixels
  • Vertical (9:16): 600 x 1067 pixels
• Introductory Text: Under 150 characters recommended (though up to 600 characters are allowed; text over 220 characters may be truncated).
• Headline: Under 70 characters recommended (up to 200 characters allowed; truncated after ~70 characters).
• Destination URL: Required (must include http:// or https://).

2. Carousel Image Ads

Carousel ads let you showcase multiple images in a swipeable sequence, telling a visual story or highlighting different product features, services, or statistics.

• Number of Cards: 2 to 10 cards per carousel.
• Card Image File Types: JPEG or PNG
• Maximum Card File Size: 10 MB per card
• Card Image Dimensions: 1080 x 1080 pixels (Square, 1:1 aspect ratio)
• Introductory Text: Under 150 characters recommended (up to 255 characters allowed).
• Card Headline: Under 45 characters for destination URL cards; under 30 characters for Lead Gen Form cards.

3. Video Ads

Video is a powerful tool for building brand affinity, explaining complex B2B solutions, and capturing attention in a busy feed.

• File Format: MP4
• File Size: 75 KB to 200 MB
• Video Length: 3 seconds to 30 minutes (though 15 to 30 seconds typically yields the highest engagement for awareness campaigns).
• Aspect Ratios & Resolutions:
  • Landscape (16:9): 640 x 360 to 1920 x 1080 pixels
  • Square (1:1): 360 x 360 to 1920 x 1920 pixels
  • Vertical (9:16): 360 x 640 to 1080 x 1920 pixels
• Frame Rate: 30 frames per second or less
• Audio Format: AAC or MPEG4
• Introductory Text: Under 150 characters recommended (up to 600 characters allowed).
• Headline: Under 70 characters recommended (up to 200 characters allowed).

4. Text Ads

Text ads are simple, cost-effective pay-per-click (PPC) or cost-per-impression (CPM) ads that appear on the top or right-hand side of the desktop view.

• Image (Optional): 100 x 100 pixels (JPEG or PNG, max 2 MB).
• Headline: Maximum 25 characters.
• Description: Maximum 75 characters.
• Note: Text ads are desktop-only formats.

5. Spotlight & Follower Dynamic Ads

Dynamic ads personalize themselves using LinkedIn member profile data (such as their profile photo, name, and company name) to drive page follows or website conversions.

• Ad Title (Headline): Maximum 50 characters.
• Description: Maximum 70 characters.
• Company Name / CTA Button: Maximum 18 characters.
• Custom Background Image (Optional): 300 x 250 pixels (JPEG or PNG, max 2 MB).

6. Lead Gen Forms (Sponsored Content & Message Ads)

Lead Gen Forms pre-fill user contact data from their LinkedIn profiles, drastically reducing friction and boosting conversion rates.

• Form Title: Maximum 60 characters.
• Form Details / Body Text: Maximum 160 characters.
• Privacy Policy URL & Text: Required (maximum 2,000 characters for policy text).
• Confirmation Message: Maximum 300 characters (plus a destination link up to 500 characters).

Best Practices for LinkedIn Ad Success

1. Design for Mobile First: Over 60% of LinkedIn traffic originates from mobile devices. Vertical and square formats (1:1 and 9:16) take up significantly more screen real estate in the mobile feed than landscape ads.
2. Include Captions on Videos: Many professionals browse LinkedIn with audio muted by default. Always burn open captions or subtitles directly into your video files.
3. Front-Load Your Value Proposition: Keep your introductory text concise. Critical messaging, hooks, and offers should appear within the first 150 characters before truncation occurs.
4. Test and Iterate: Don’t rely on just one creative variant. A/B test different aspect ratios, headlines, and calls-to-action (CTAs) to discover what resonates best with your target buyer personas.