Short answer
For ABM, use single image and Thought Leader Ads for steady reach to the committee, video for awareness, document ads to deliver useful content inside the feed, and conversation or message ads sparingly for tier 1 accounts. Prepare images at 1200 × 628, 1200 × 1200 and 720 × 900, keep headlines near 70 characters and intro text near 150, and rotate several ads so frequency doesn't burn out a small list.
Formats and their ABM job
| Format | Best ABM job | Key specs |
|---|---|---|
| Single image | Steady reach, retargeting identified accounts | 1200 × 628, 1200 × 1200, 720 × 900; up to 5 MB; headline ~70, intro ~150 characters recommended |
| Thought Leader Ads | A trusted face in front of the committee | Promotes a member's post with approval. Details |
| Carousel | Several proof points or use cases | 2–10 cards, 1080 × 1080, up to 10 MB each |
| Document | Deliver a guide or report in the feed | PDF, PPT, PPTX, DOC, DOCX; up to 100 MB and 300 pages |
| Video | Awareness and recall | MP4, 3 seconds to 30 minutes, up to 200 MB |
| Message and conversation ads | Invitations for tier 1 accounts | Message text up to 1,500 characters; conversation ads up to 8,000; 300 × 250 banner on desktop |
Specs as summarised by Brandwatch (updated April 2026). Check Campaign Manager before production; LinkedIn changes limits.
A format plan by stage
- Unaware accounts: single image and video to the whole list at low frequency.
- Engaged accounts: document ads with a cluster-specific guide; Thought Leader Ads from a product expert.
- In-market accounts, including those identified from AI traffic: single image with a specific offer, plus carousel proof.
- Tier 1 accounts: one well-timed conversation ad with an event or briefing invitation.
Creative that survives a small list
- Rotate three to five ads per campaign; small ABM audiences tire of one ad fast.
- Write for the account's situation, not your feature list: "Audit in Q2? Here's the 6-week plan" beats "The leading compliance platform".
- Produce every size from one master with the ad image resizer.
- Keep text off the edges; the same image is cropped differently in feed, mobile and Audience Network placements.
Questions
What size should LinkedIn single image ads be?
1200 × 628 landscape, 1200 × 1200 square or 720 × 900 vertical, as JPG, PNG or GIF up to 5 MB.
How long can LinkedIn ad text be?
For single image ads, intro text up to 600 characters (about 150 recommended) and headline up to 200 (about 70 recommended).
Are document ads good for ABM?
Yes for the middle of the funnel: buyers can read a guide in the feed, and you can choose whether to gate it. They suit 1:few clusters with tailored content.
Should we use message ads in ABM?
Only for small, high-value tiers with a specific offer, such as an event invitation. Overuse annoys the people you most want to win.
Facts checked against the sources below on 19 October 2026. Ad platforms change quickly: if something here no longer matches what you see, tell us and we will update it.
