Create custom audiences by entering keywords, URLs, or apps related to your product—Google finds users with matching interests.
What are Custom Segments in Google Ads? Custom Segments let you build custom audiences by entering keywords, competitor URLs, or apps. Google finds users matching your criteria. More specific than Affinity Segments, 15-40% higher CVR but smaller reach. Expanded Display availability Dec 2025. Best for niche products without pre-built segments.
Custom Segments let you build custom audiences by defining specific interests, websites, apps, or search terms relevant to your product, then Google uses those inputs to find users who match your criteria. Three creation methods: (1) Keywords—enter topics/interests (e.g., "ultralight backpacking," "fastpacking"), Google targets users interested in those topics; (2) URLs—enter competitor websites or related sites (rei.com/adventures, alltrails.com), Google targets users who visit similar sites; (3) Apps—enter relevant apps (Strava, AllTrails), Google targets users of those apps and similar apps. Available in Display, Gmail, Video, Demand Gen, and Performance Max campaigns. Expanded availability December 2025 for Display campaigns.
Unlike pre-built Affinity Segments (broad categories like "Outdoor Enthusiasts"), Custom Segments let you target ultra-specific niches Google doesn't have pre-built segments for. Performance: 15-40% higher conversion rates than broad Affinity Segments due to precision, but 60-80% smaller audience reach. Best for niche products where pre-built segments are too broad or don't exist.
Official Source: Definition verified from Google Ads Help Center (Last verified: January 2026)
"Custom segments help you reach your ideal audience by entering relevant keywords, URLs, and apps."
Vegan protein powder brand uses Custom Segments to target vegan athletes, achieving 3.2x higher CVR than "Health & Fitness Buffs" Affinity.
Affinity "Health & Fitness Buffs": 1.2M potential reach, $8,000 spend, 68 conversions, $118 CPA, 2.1% CVR. Custom Segment (keywords: vegan protein, plant-based athlete, vegan bodybuilding, vegan fitness nutrition): 180K potential reach, $8,000 spend, 185 conversions, $43 CPA, 6.8% CVR. Result: Custom Segment delivered 3.2x higher conversion rate and 63% lower CPA despite 85% smaller audience by targeting specific vegan fitness niche.
Custom Segments solve the niche targeting problem: Google's 150+ pre-built Affinity Segments cover mainstream interests ("Sports Fans," "Foodies") but miss specific niches ("vegan athletes," "ultralight backpackers," "retro gamers"). Custom Segments fill this gap by letting you define your exact niche via keywords/URLs. Example: Selling ultralight backpacking gear. "Outdoor Enthusiasts" Affinity Segment includes car campers, casual hikers, hunters (too broad). Custom Segment with keywords "ultralight backpacking, fastpacking, gram weenie, UL gear" targets the specific ultra-light hiking community (15% of outdoor enthusiasts). Result: 3x higher conversion rate from precision targeting despite 85% smaller audience. The December 2025 policy expansion made Custom Segments available to more Display advertisers, making them essential for niche product marketing in 2026.
Adding too many unrelated keywords (dilutes targeting precision)
Using generic broad keywords that match Affinity Segments (use pre-built Affinity instead)
Not combining multiple Custom Segments with Affinity for layered targeting
Expecting large reach from ultra-niche Custom Segments (precision trades off against scale)
Use 5-15 highly related keywords/URLs per Custom Segment (focused beats scattered)
Enter competitor websites as URLs to target users browsing similar products
Create multiple Custom Segments for different niche angles, test performance
Layer Custom Segment + Affinity for maximum precision (broad lifestyle + specific niche)
Use Custom Segments for products too specific for pre-built segments
Pre-built Google audience targeting based on users' long-term interests, passions, and lifestyle habits for awareness and consideration campaigns.
Pre-built Google audiences targeting users actively researching or comparing products/services, showing high purchase intent.
Groups of people you can target or observe in Google Ads based on their interests, behaviors, demographics, or interactions with your business.
Use pre-built Affinity Segments when your product fits mainstream interest categories: "Foodies" for restaurants, "Auto Enthusiasts" for car parts, "Pet Lovers" for pet products. Use Custom Segments when: (1) Your niche is too specific for pre-built segments (vegan athletes, minimalist travelers, retro gamers); (2) You know exact competitor websites/apps your customers use; (3) You need hyper-targeted small audience (1,000-50,000 users) vs broad reach. Performance trade-off: Affinity = larger reach (100K-5M users), lower precision (1-2% CVR). Custom = smaller reach (10K-500K users), higher precision (2-5% CVR). Layering strategy: Use both simultaneously—Affinity "Outdoor Enthusiasts" (broad lifestyle) + Custom Segment keywords "ultralight backpacking" (specific niche) = precision targeting of outdoor lovers specifically interested in ultralight gear. Test both separately first to understand which performs better for your specific product, then layer for maximum performance.
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