Lead cost and completion
| Format with a lead gen form, content offer | Cost per lead | Form completion | Form opens per lead | Accounts |
|---|---|---|---|---|
| Document ad | $180 | 20.3% | 5 | 96 |
| Single image sponsored content | $189 | 8.3% | 12 | 141 |
| Video sponsored content | $119 | 4.6% | 22 | 10 |
| Thought leader ad, single image | $94 | 11.4% | 9 | 16 |
| Message ad | $56 | — | — | 22 |
Pooled, document ads and single image look close on cost per lead, $180 against $189. The paired comparison is the one that matters: inside the same accounts running both, document ads came in 22% cheaper per lead on content offers. Account quality cannot explain that.
The completion rate is the stand-out. 20.3% against 8.3% is two and a half times better on the same mechanic, the same pre-filled form and the same audience.
Why fewer opens produce cheaper leads
| Format | Form open rate | Completion | Accounts |
|---|---|---|---|
| Video with a form | 0.45%, highest | 4.6%, lowest | 28 |
| Single image with a form | 0.39% | 8.3% | 194 |
| Thought leader ad with a form | 0.39% | 11.4% | 16 |
| Document ad with a form | 0.14%, lowest | 20.3%, highest | 157 |
Open rate and completion run in opposite directions, almost perfectly. Video gets the most opens and the fewest finishes. Document ads get the fewest opens and the most finishes.
The reason is that a document ad does the qualifying before the form. The reader swipes through several pages of the thing you are offering, so by the time they tap the form they already know whether they want it. A single image makes the same promise in one frame and a lot of people open the form to find out what they are actually signing up for, then leave. Against an 88% abandonment rate across all formats, cutting the openers who were never going to finish is worth more than adding openers.
The highest engagement rate in the feed
| Feed format, all objectives except lead generation | Engagement rate | Total CTR | CPM | Accounts |
|---|---|---|---|---|
| Document ad | 6.75% | 3.32% | $61.77 | 154 |
| Thought leader ad, single image | 4.69% | 4.49% | $62.62 | 408 |
| Thought leader ad, video | 2.95% | 2.70% | $60.02 | 203 |
| Single image sponsored content | 1.16% | 0.65% | $48.02 | 774 |
| Video sponsored content | 0.92% | 0.41% | $40.93 | 504 |
| Carousel | 0.74% | 0.43% | $54.01 | 106 |
6.75% is the highest engagement rate of any feed format, above even thought leader ads. Against the general benchmark bands, anything over 3% is strong and under 1% is below average, so a document ad sits at roughly double the strong threshold. Every swipe counts as an engagement, which flatters the number, but the dwell is real.
Where document ads fail
| Format | Landing page CTR | Cost per landing page click |
|---|---|---|
| Document ad | 0.06% | $101 |
| Single image sponsored content | 0.37% | $13.63 |
| Thought leader ad, single image | 0.30% | $25.02 |
A $101 landing page click is not a typo. Document ads are the worst traffic format in the feed by a wide margin, because the whole design keeps the reader inside LinkedIn. If your objective is website visits, do not use one. If your objective is a form fill or engagement, the same behaviour is the reason they work.
Cost by objective
| Document ad, by objective | CPM | Landing page CTR | Cost per landing page click | Engagement rate | Accounts |
|---|---|---|---|---|---|
| Website visits | $28.37 | 0.15% | $17.99 | 6.60% | 44 |
| Brand awareness | $24.18 | 0.03% | $72.39 | 5.85% | 40 |
| Lead generation | $52.74 | form opens in LinkedIn | — | 5.38% | 241 |
| Engagement | $83.77 | 0.05% | $206 | 7.55% | 95 |
The engagement objective buys the highest engagement rate and the worst of everything else, at a $83.77 CPM and a $206 landing page click. Brand awareness is the cheapest way to put a document in front of people at $24.18. Lead generation is where most document spend sits, across 241 accounts, and it is the right place for it.
When to use one
Use a document ad for a content offer with a lead gen form. 22% cheaper per lead paired, 20.3% completion, and the lowest opens-per-lead ratio of any format at 5 against 12 for single image. This is the case and it is strong.
Use one for engagement and retargeting pool building, on a brand awareness objective at a $24.18 CPM rather than engagement at $83.77.
Do not use one for website traffic at $101 a landing page click, and do not use one for demo requests, where the panel withholds the document figure for lack of base and the formats that work are message ads at $175 and conversation ads at $365.
If you run lead gen forms off single image creative and have never tested a document ad, that is the cheapest test available to you.
All figures are from Kiin Labs: a panel of 1,071 B2B LinkedIn advertising accounts, $79M of spend, 22,942 campaigns, 1.34 billion impressions, 2.4 million landing page clicks and 139,231 form submissions, for the 12 months to 7 September 2026. LinkedIn Audience Network is excluded throughout. Figures are medians, not averages, because the top 10% of accounts spend 64% of the money. Where a comparison says "paired", both options ran inside the same account, so account quality cannot explain the gap.