Lookalike audiences are advertising audiences created by ad platforms that find users similar to a "seed" audience you provide. If your seed audience is people who purchased from you, the platform finds other users with similar demographics, behaviors, and interests.
Why this matters:
Lookalike audiences bridge the gap between retargeting (warm audiences) and broad prospecting (cold audiences). They combine the targeting precision of retargeting with the scale of prospecting.
Navigate to Advertising > Audiences. The Audiences tab shows all your audiences organized by type:
Click Create Lookalike to start building a new lookalike audience.
Choose a descriptive name that identifies both the seed and the expansion. Examples:
The seed audience is the source that platforms use to find similar users. Choose from your existing retargeting audiences:
| Seed Type | Best For | Minimum Size |
|-----------|----------|--------------|
| Purchasers | Finding more buyers | 1,000+ |
| High-value customers | Quality over quantity | 500+ |
| Email subscribers | Newsletter promotion | 2,000+ |
| Content readers (by topic) | Content-matched prospecting | 5,000+ |
| Lead magnet downloaders | Mid-funnel expansion | 1,000+ |
Tip: Larger seed audiences give platforms more data to work with, but quality matters more than quantity. A seed of 1,000 purchasers outperforms 10,000 random visitors.
The lookalike percentage determines how similar the new audience is to your seed:
| Percentage | Similarity | Typical Size | Best For |
|------------|------------|--------------|----------|
| 1% | Most similar | 2-3M (US) | Highest conversion, limited scale |
| 2-3% | Very similar | 5-8M (US) | Balanced approach |
| 5% | Moderately similar | 12-15M (US) | More scale, lower conversion |
| 10% | Broad similarity | 25-30M (US) | Maximum reach, awareness campaigns |
Recommendation: Start with 1-2% lookalikes for conversion campaigns. Expand to 5% only after exhausting smaller audiences.
Lookalikes are built per country. Select your primary market:
You can create separate lookalikes for each country you target.
Click Create Lookalike. ILLIXIS queues the audience for creation on connected platforms:
Meta's lookalike algorithm analyzes:
Requirements:
Creation time: 1-24 hours depending on seed size.
LinkedIn's algorithm focuses on:
Requirements:
Best for: B2B campaigns targeting professional audiences.
Google deprecated Similar Audiences in 2023. Instead, ILLIXIS uses your seed audience data to inform:
Note: Google's approach is less direct than Meta or LinkedIn. Results vary based on campaign type and bidding strategy.
Click any lookalike audience to view:
Overview:
Platform Status:
Performance (if used in campaigns):
1. Quality Seeds Over Large Seeds
A seed of 500 purchasers creates better lookalikes than 50,000 page visitors. Platforms need signal, not noise. Use audiences with clear conversion intent.
2. Layer Lookalikes Strategically
Don't target all lookalike percentages simultaneously. Start with 1% until frequency gets too high, then expand to 2-3%, then 5%.
3. Exclude Existing Customers
Always exclude your retargeting audiences and customer lists from lookalike campaigns. You don't want to pay for impressions to people who already converted.
4. Test Multiple Seeds
Create lookalikes from different seeds:
Compare performance to find your best seed source.
5. Refresh Seeds Quarterly
Lookalikes are only as current as their seeds. Update your seed audiences with recent converters to keep lookalikes relevant.
6. Match Creative to Audience
Lookalike audiences are still cold prospects. Use awareness and consideration messaging, not bottom-funnel conversion copy.
| Task | Schedule | What It Does |
|------|----------|--------------|
| Audience Clustering | Nightly 2:30 AM UTC | Semantically clusters published content and creates GA4 audiences |
| Platform Sync | On-demand (when you create/update audiences) | Pushes audience definitions to Meta, LinkedIn, Google |
Automatic clustering:
Note: Lookalike expansion happens on the ad platform side (Meta, LinkedIn) after ILLIXIS syncs the seed audience. ILLIXIS does not control platform-side lookalike refresh timing.
Q: How long until my lookalike is ready? Meta: 1-24 hours. LinkedIn: 24-48 hours. Status shows in the audience detail view.
Q: Why is my lookalike smaller than expected? Platform availability varies. Smaller markets have fewer users matching your seed profile. Check country selection and try expanding the percentage.
Q: Can I edit a lookalike after creation? No. Create a new lookalike with different settings. Delete the old one if no longer needed.
Q: Do lookalikes update automatically? Platform-side yes, but based on your original seed at creation time. To incorporate new seed members, create a fresh lookalike.
Q: What if my seed audience is too small? Combine audiences or wait until you have more conversions. Poor-quality lookalikes waste ad spend.
What This Does
Location: Advertising → Prospecting Tab → Create Campaign
Location: Advertising → Dashboard → Google Ads Tab → Project → Ad Builder
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