Placement Targeting vs Similar Segments: Manual Control After the Sunset
In short: These sat at opposite ends of the control spectrum for the same budget. Placement targeting is the most manual buying Display and YouTube offer - you name the properties and delivery stays there. Similar segments were the opposite: you handed Google a seed list and it derived an expanding audience on its own, until Google removed the feature in 2023. Only one of these is a live choice, but the tension they represent - hand-picked certainty versus automated expansion - is still the central Display decision, with optimized targeting now playing the automation side. Name the venues when you know them; when you would have reached for similar segments, the modern lever is the optimized targeting toggle.
By the AdFlint research team · Fact-checked against current Google and Meta platform behavior · Last reviewed July 2026
Placement Targeting
Names the specific websites, YouTube channels, videos, or apps where your Google Display or video ads may appear, instead of letting Google choose inventory.
You add managed placements to an ad group and delivery is limited to that list, making it the most controlled form of Display buying available. Use it when a handful of sites genuinely reach your buyer, or to rebuild an audience from a placement report that already performs. The failure mode is a list so narrow the campaign cannot spend and the data never becomes conclusive.
Full definitionSimilar Segments
Google's retired audience expansion feature, which generated lookalike-style segments from a seed list before being removed in 2023 in favor of automated targeting.
Similar segments once derived a resembling audience automatically from a remarketing or Customer Match seed, and Google sunset them so campaign-level automation could do that expansion instead. Your seed lists remain valuable as signals feeding optimized targeting and Smart Bidding rather than as sources for a derived list. Advertisers still hunting for the setting almost always want optimized targeting or Customer Match.
Full definitionSide by side.
The differences that actually change what happens in your account.
| Placement Targeting | Similar Segments | |
|---|---|---|
| Status today | Live, with caveats on some conversion-focused video types. | Removed in 2023 - not creatable or applicable anywhere. |
| What you specified | Sites, channels, videos, and apps, named row by row. | One seed list - Google derived everything else. |
| Control philosophy | Maximum manual control: nothing serves off the named list. | Maximum delegation: the audience grew itself from the seed. |
| How it scaled | Only as fast as you added rows by hand. | Automatically, as the derived pool refreshed against the seed. |
| The failure you managed | A list too narrow to spend, leaving the test inconclusive. | Expansion toward resemblance you could not inspect or veto member by member. |
| Modern successor | Itself - still how you allowlist inventory. | Optimized targeting, plus Demand Gen's lookalike segments, though both now default to guiding delivery rather than hard-capping it. |
| Data required from you | None - the list is built from outside knowledge. | A seed list large enough to derive from, built by your tag or uploads. |
What actually separates them.
Placement targeting answers where and similar segments answered who - they constrained entirely different dimensions of the same auction.
Placements remain a live control while similar segments have been unusable since 2023, so any playbook pairing them needs rewriting, not just updating.
A placement list never expands on its own, while similar segments existed precisely to expand on their own - opposite defaults that attract opposite temperaments.
Placement buying fails visibly as underspend, while expansion-style buying fails invisibly as spend on unverifiable resemblance - the diagnostic work is completely different.
The automation that replaced similar segments also reaches into placement campaigns: leaving optimized targeting on relaxes a placement allowlist into a suggestion.
Which one should you use?
Use Placement Targeting when
- A short list of publications or channels genuinely concentrates your buyers.
- You need an auditable allowlist you can defend to a client or compliance reviewer.
- You are rebuilding from a placement report where specific properties already convert.
- You want sponsorship-style adjacency rather than audience-chasing reach.
- You have no first-party data and still need controlled delivery on day one.
Use Similar Segments when
- You are auditing a legacy account structure that referenced similar audiences.
- You are translating a pre-2023 strategy document into current platform features.
- You are explaining a delivery shift in an old campaign that lost its derived segments.
- You want automated expansion from a seed today, which is optimized targeting's job now.
Common questions.
Can I still layer a similar audience over my placement campaign?
No - similar segments were removed in 2023 and cannot be applied to anything. The modern equivalent of that layering is leaving optimized targeting on in the ad group, which lets Google expand beyond your placements using your lists and conversion data as signals. Be deliberate about it, because that same toggle dissolves your allowlist.
Why did my placement-only ad group start serving on other sites?
Almost always because optimized targeting is enabled, which turns manual placements into signals rather than limits. Turn it off at the ad group level if you want strict allowlisting. It is worth rechecking after campaign-type changes, since defaults differ by goal.
Which campaign types still accept managed placements?
Display ad groups still take them, and reach and awareness video formats still allow channel and video placements. Some conversion-focused video campaign types no longer accept content targeting at all, placements included. Confirm what the specific campaign type exposes before building a plan around placement control.
What should I use instead of similar segments for prospecting?
Optimized targeting is the designated successor: seed it with your best lists and let it hunt predicted converters. Demand Gen campaigns also offer lookalike segments built from seeds with a reach setting you choose, though they now default to guiding Google's AI rather than enforcing a hard cap. Either way, the quality of the seed list is still what determines the quality of the expansion.
Or stop choosing between them.
AdFlint picks the setting, writes the ads, and keeps optimizing inside the Google and Meta accounts you already own.
Related comparisons
- Affinity Audiences vs In-Market Audiences
- Custom Segments vs In-Market Audiences
- Customer Match vs In-Market Audiences
- In-Market Audiences vs Remarketing Lists
- In-Market Audiences vs Similar Segments
- Demographic Targeting vs In-Market Audiences
- In-Market Audiences vs Life Events Targeting
- In-Market Audiences vs Optimized Targeting