> Quick answer: Add affinity segments for awareness and in-market segments for conversions. Go to Campaigns > Audiences, keywords, and content > Audiences > Edit audience segments. Start in Observation mode to collect data, then switch to Targeting mode once you know which segments convert.
Interest targeting in Google Ads lets you reach users based on who they are, not just what they typed. Add affinity or in-market segments to any campaign in under five minutes. Here's the full setup.
What Is Interest Targeting in Google Ads?
Interest targeting shows your ads to people based on their habits, passions, and purchase behavior. It adds context to every impression beyond the keyword alone.
Understanding audience segments
Per Google's Ads Help Center, audience segments group users by lifestyles, purchase intent, demographics, and habits. Google builds these segments from signals like browsing history, app usage, and search patterns. Four main types are available: affinity, in-market, custom, and detailed demographics. Each one targets a different stage of the purchase journey.
Affinity vs. in-market audiences
Affinity segments target long-term interests and passions. In-market segments target people actively researching or comparing products right now. Both are available across Search, Display, Video, and Standard Shopping campaigns.
Why interest targeting matters
Keyword targeting alone misses context. Two people can search "running shoes." One is casually browsing. The other is ready to buy. Interest targeting helps you reach the right one more consistently. Layer it on top of keywords and your impressions get sharper without forcing you to cut reach drastically.
Types of Interest-Based Audience Segments
Google Ads gives you three practical options for interest-based targeting. The right choice depends entirely on your campaign goal.
Affinity segments: reaching passionate audiences
Affinity segments reach users based on long-term, demonstrated interest in a topic. Think fitness enthusiasts, travel buffs, or home improvement fans. Per Google's Ads Help Center, pairing an affinity segment with related keywords sharpens your focus without cutting reach too aggressively. Use them for awareness and consideration campaigns where building familiarity matters.
In-market segments: capturing purchase intent
In-market segments reach consumers actively comparing or researching products. They are designed for conversion goals. Google's documentation references a Toyota case study where in-market audiences drove a 67% increase in conversion rate and a 34% reduction in CPA. When you need results now, in-market is your starting point.
Custom segments as an alternative
Custom segments let you define audiences using keywords, competitor URLs, or relevant apps. If no standard segment matches your niche closely enough, build your own. Custom segments are available for Display, Video, and Discovery campaigns and give you precise control over who qualifies.
Step-by-Step: How to Add Interest Targeting
This setup takes about five minutes inside Google Ads.
Navigate to the Audiences section
Open Google Ads. In the left navigation, click Campaigns. Select Audiences, keywords, and content. Then click Audiences and click Edit audience segments.
Select your campaign and ad group
A setup panel opens on the right side of the screen. Choose your campaign first, then select the specific ad group you want to apply targeting to. Audience segments apply at the ad group level in most campaign types, including Search, Display, and Video.
Choose and add audience segments
Browse segments by category or search by name. Open the Audience ideas tab to see segments Google recommends based on your existing audiences, your website, and similar advertisers in your vertical. Check each segment you want to include.
Save your targeting settings
Click Save. Your segments activate immediately. Future impressions reflect your interest targeting criteria from that point forward. No waiting period required.
Targeting vs. Observation Mode
Google Ads gives you two modes when you add an audience segment. Choosing the wrong one early on is a common and costly mistake.
When to use Targeting mode
Targeting mode restricts your ad group to only the audiences you selected. Use it when you've already confirmed which segments convert and want to concentrate your budget on those specific people.
When to use Observation mode
Observation mode does not restrict who sees your ads. Per Google's Ads Help Center, it lets you monitor how different audience segments perform without limiting reach. Your ad group runs as normal while collecting audience-level data in the background.
How observation helps optimize campaigns
Start every new campaign in Observation mode. Collect data for two to four weeks. When one segment clearly outperforms the rest, switch that ad group to Targeting mode and focus your spend there. This approach reduces wasted budget and builds on real performance signals instead of assumptions.
Interest Targeting Best Practices
Combine interest targeting with keywords
Layer an in-market segment over a keyword campaign. This targets both purchase intent and behavioral interest at once. It's especially effective in Search campaigns where commercial intent is already high and every incremental signal helps.
Use audience ideas to discover segments
The Audience ideas feature surfaces segments you would not think to search for manually. Google analyzes your current audiences, your website, and similar advertisers in your vertical. Always check it before locking in your final segment list. New segments you had not considered often show up there.
Monitor and adjust based on performance
Pull your audience performance report every week. Low-performing segments drain budget without delivering conversions. Observation mode data tells you exactly which ones to cut before they cause real damage to your numbers.
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Frequently Asked Questions
What is the difference between affinity and in-market audiences in Google Ads?
Affinity audiences target users based on long-term interests and lifestyles. In-market audiences target users actively researching or comparing products right now. Use affinity for awareness campaigns and in-market when you want conversions.
Should I start with Targeting mode or Observation mode?
Start with Observation mode. It collects performance data on how each audience segment behaves without restricting your reach. Once you identify which segments convert well, switch to Targeting mode to focus your budget on those audiences.
Can I use interest targeting on Search campaigns?
Yes. Affinity and in-market segments are both available for Search campaigns. Layering an audience segment over your keywords adds behavioral context to your targeting without requiring you to reduce your keyword list.
What are custom segments in Google Ads?
Custom segments let you build your own audience using keywords your ideal customer searches, competitor URLs they visit, or relevant apps they use. They are available for Display, Video, and Discovery campaigns and work well when no standard segment matches your niche closely enough.