Audience Targeting

Custom Segments vs Affinity Audiences: Build Your Own or Pick Prebuilt

In short: Both are ways to hand Google a description of the person you want on Display, Video, and Demand Gen. Affinity means choosing from Google's fixed menu of long-term interest buckets; custom segments mean writing your own definition from keywords, URLs, and apps, and letting Google assemble the matching people. The custom route can express things the menu never will - competitor brands, niche categories, your own proven Search terms - but it only works as well as the coherence of your inputs. If a prebuilt segment genuinely describes your buyer, take the free lunch; the moment you find yourself squinting to make a menu option fit, build a custom segment instead.

By the AdFlint research team · Fact-checked against current Google and Meta platform behavior · Last reviewed July 2026

Affinity Audiences

Reaches people with a durable long-term interest or lifestyle, such as cooking enthusiasts or luxury shoppers, rather than anyone showing immediate purchase intent.

Google builds affinity segments from sustained browsing and viewing habits, so they describe who someone is rather than what they are shopping for this week. You use them on Display, Video, and Demand Gen for upper-funnel reach when a product needs awareness before consideration. The mistake is expecting direct-response performance and then judging them on last-click conversions they were never going to win.

Full definition

Custom Segments

Lets you define your own Google audience from keywords people search, websites they browse, or apps they use, instead of picking a prebuilt segment.

You supply search terms, URLs, or app IDs, and Google assembles an audience of people whose behavior matches those signals across Display, Video, and Demand Gen. It is the closest thing to keyword targeting outside Search, and it replaced the older custom affinity and custom intent segments. Most accounts overload one segment with unrelated inputs, which blurs the signal Google builds against.

Full definition

Side by side.

The differences that actually change what happens in your account.

	Affinity Audiences	Custom Segments
What you enter	Nothing but a selection - you browse Google's segment list and tick one.	Your own raw material: search terms, competitor URLs, app names.
Who defines the audience	Google, from sustained browsing and viewing habits, on its own schedule.	You define the signal; Google assembles and refreshes the people matching it.
How narrow it can get	Only as narrow as the taxonomy goes - broad lifestyle buckets by design.	As narrow as your inputs - a handful of niche terms or two competitor domains.
Competitor conquesting	Not expressible. There is no bucket for another company's customers.	The core use case: enter competitor brand terms and URLs and reach people whose behavior matches.
Consistency across campaign types	The same segment means the same thing everywhere it is available.	Inputs are interpreted differently by campaign type - search-term inputs can mean people who actually searched those terms on Google in some campaign types, and interest-style matching in others.
Maintenance burden	None. Google updates membership and you never touch it.	Ongoing. Stale terms and dead URLs quietly drag the signal off target.
Failure mode	Too broad for the budget, judged on last-click conversions, and killed unfairly.	One segment stuffed with unrelated inputs, blurring the pattern Google builds against.

What actually separates them.

Affinity picks from a fixed menu while custom segments compile an audience from signals you supply, so only the custom route can express a niche the taxonomy missed.

Custom segments absorbed the older custom affinity and custom intent types, so one segment now stretches from lifestyle-like to intent-like purely based on what you feed it.

Search-term inputs in a custom segment can mean people who genuinely searched those terms on Google in certain campaign types - a level of intent affinity can never encode.

Competitor URLs and brand keywords are only expressible through custom segments; affinity has no mechanism for naming another company.

Affinity membership is durable because it describes who someone is, while custom segments built on search behavior skew recent, so the same person cycles in and out.

Which one should you use?

Use Affinity Audiences when

You are running broad awareness for a lifestyle product and reach matters more than precision.
You have no proven keywords or competitor list to seed a custom definition with.
You want zero-maintenance targeting that Google keeps fresh without your involvement.
You are layering segments as observation first, to learn which interest groups actually respond before committing budget.
You are buying video reach where broad, cheap coverage of a lifestyle bucket is exactly the plan.

Use Custom Segments when

You want competitors' shoppers - their brand terms and domains go straight into the segment definition.
Your niche has no matching prebuilt segment and every menu option is a stretch.
You have Search keywords that already convert and want that same intent working on YouTube, Display, and Demand Gen.
In-market categories exist for your vertical but are broader than your actual product line.
You want reporting to tell you which theme works, so you build one tight segment per theme instead of one blended list.

Common questions.

Are custom intent and custom affinity audiences still a thing in Google Ads?

Not as separate products. Google merged them into custom segments, and the segment now behaves more intent-like or more affinity-like depending on the inputs you give it and the campaign type using it. Old guides that treat them as two different settings are describing a UI that no longer exists.

Can I put competitor names in a custom segment?

Yes, and it is one of the main reasons the feature exists. Enter competitor brand terms and competitor URLs, and Google builds an audience of people whose search and browsing behavior matches those signals. Be clear about the mechanics: entering a URL does not mean you only reach literal visitors of that site - it means people who browse content like it.

How many keywords or URLs should go in one custom segment?

Enough to describe one coherent theme and no more. The practical rule is one theme per segment: when you blend competitor terms, category terms, and aspirational lifestyle terms into one list, Google averages them into a fuzzy audience and your reporting cannot tell you which idea deserved the credit. Split themes into separate segments and let performance pick the winner.

Why does the same custom segment behave differently in my Video and Display campaigns?

Because Google interprets the inputs according to the campaign's type and goal. In some campaign types your search-term inputs are matched against what people actually searched on Google; in others the same words are treated as interest signals. The segment name is identical but the population it resolves to is not, so judge each campaign's audience on its own results.

Or stop choosing between them.

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