Facebook Custom Audiences let you target people who already know your brand — website visitors, email subscribers, app users, or video viewers — while Lookalike Audiences find new people who resemble your best customers. Together, they form the foundation of profitable Facebook and Instagram advertising, typically delivering 40-60 % lower cost-per-acquisition than interest-based targeting for Indian advertisers running campaigns above ₹50,000/month. Last updated October 2026.
What Are Facebook Custom Audiences?
Custom Audiences are targeting groups created from your own data. You supply the source, and Facebook matches it against its user base. Types of Custom Audiences:
- Website Custom Audience: People who visited your website (tracked via Meta Pixel or Conversions API). You can target all visitors, specific page visitors (e.g., pricing page visitors), or visitors who triggered specific events (add-to-cart, initiated checkout). Retention window: 1-180 days.
- Customer List: Upload email addresses, phone numbers, or Facebook User IDs from your CRM or email list. Facebook matches them (typically 40-70 % match rate for Indian phone numbers, lower for emails). Minimum 1,000 contacts recommended.
- App Activity: Target users based on actions within your mobile app (if you have one integrated with Facebook SDK).
- Engagement: People who interacted with your Facebook/Instagram content — watched your videos (25/50/75/95 %), opened a Lead Form, interacted with your Instagram profile, or engaged with an event. Retention: up to 365 days.
- Offline Activity: Match CRM or POS transaction data with Facebook users for offline-to-online attribution and retargeting.
What Are Lookalike Audiences?
Lookalike Audiences use Facebook’s algorithm to find users who share characteristics with a source audience you provide. The source can be any Custom Audience, but high-value sources produce better results. Key parameters:
- Source audience: Your seed Custom Audience. Best sources: purchasers, high-LTV customers, qualified leads. Minimum source size: 100 people in one country, but 1,000-5,000 produces significantly better results.
- Lookalike percentage: How closely the Lookalike matches the source. 1 % = most similar (top 1 % of the country’s Facebook population), 10 % = broader reach but less similar. In India, 1 % Lookalike = approximately 4-5 million people.
- Country: Lookalikes are country-specific. For Indian campaigns, select India as the location.
Custom Audiences vs Lookalike Audiences: When to Use Each
Use Custom Audiences When:
- Retargeting warm audiences (website visitors who did not convert, cart abandoners)
- Upselling or cross-selling to existing customers
- Re-engaging lapsed customers or inactive email subscribers
- Building engagement with video viewers or page followers
- Running sequential messaging campaigns (show different ads based on previous interactions)
Use Lookalike Audiences When:
- Prospecting for new customers who resemble your best buyers
- Scaling campaigns beyond your existing audience
- Launching in new Indian cities where you have no existing customer base
- Finding new leads for high-ticket services (where broad targeting wastes budget)
Use Both Together (the Power Strategy):
Create a funnel: Lookalike Audiences for top-of-funnel prospecting → engagement/website Custom Audiences for middle-of-funnel nurturing → purchase/add-to-cart Custom Audiences for bottom-of-funnel conversion campaigns. Exclude purchasers from prospecting campaigns and website visitors from Lookalike campaigns to avoid overlap.
Setting Up High-Performing Custom Audiences for India
Website Custom Audiences
Prerequisites: Meta Pixel installed on all pages, Conversions API (CAPI) configured for server-side tracking (essential after iOS 14.5 and ad-blocker prevalence). Use Google Tag Manager to manage pixel events.
Recommended audiences for Indian e-commerce:
- All website visitors — last 30 days (retargeting)
- Product viewers — last 14 days (consideration stage)
- Add-to-cart — last 7 days (high intent, urgency messaging)
- Checkout initiated but not purchased — last 3 days (abandoned cart recovery)
- Purchasers — last 180 days (exclude from prospecting, use for Lookalikes and upselling)
For lead generation businesses (agencies, real estate, education):
- Key page visitors (pricing, services, contact) — last 30 days
- Blog visitors — last 60 days (nurture with more content)
- Form submitters — last 180 days (for Lookalike seed and exclusion)
Customer List Audiences
Hash and upload customer lists through Meta Ads Manager. Tips for better match rates in India:
- Include phone numbers with country code (+91…) — Indian phone number match rates are 50-70 %, significantly higher than email match rates (20-40 %).
- Include both email and phone when available — Meta matches on multiple identifiers.
- Clean your list first: remove duplicates, invalid formats, and generic emails (info@, admin@).
- Update customer lists monthly for best results.
Creating Effective Lookalike Audiences for the Indian Market
Best Seed Audiences (Ranked by Quality)
- Purchasers with highest lifetime value (top 25 % by revenue)
- All purchasers in the last 180 days
- Qualified leads (people who completed forms and were contacted by sales)
- Website visitors who spent more than 2 minutes on site
- Video viewers who watched 75 %+ of your product/explainer videos
Lookalike Size Strategy for India
- 1 % Lookalike (4-5 million): Highest quality, lowest reach. Use for expensive products/services where you need precise targeting. Best for: real estate, luxury weddings, SaaS, B2B services.
- 2-3 % Lookalike (8-15 million): Good balance of quality and scale. Recommended starting point for most Indian campaigns.
- 5-10 % Lookalike (20-50 million): Broad reach, lower similarity. Use with additional interest or demographic layering. Best for: FMCG, mass-market e-commerce, app installs.
Create multiple Lookalikes from the same seed (1 %, 3 %, 5 %) and run them in separate ad sets to compare performance. The optimal size depends on your industry, budget, and acceptable CPA.
Advanced Strategies for Indian Advertisers
- Value-based Lookalikes: If you upload customer lists with purchase values, Facebook can create Lookalikes optimized for high-value customers rather than just similarity. Include the “value” column in your customer list CSV.
- Stacked Lookalikes: Create Lookalikes from multiple sources (purchasers, high-engagement visitors, video viewers) and combine them in one campaign to find the best overlap.
- City-level Lookalikes: For businesses serving specific Indian cities, layer Lookalike audiences with geographic targeting. A 1 % India-wide Lookalike restricted to Mumbai captures the most similar users in that specific city.
- Exclusion layering: Always exclude existing customers from Lookalike prospecting campaigns, and exclude Lookalike audience members from retargeting campaigns to avoid audience overlap and budget waste.
Frequently Asked Questions
What is the minimum audience size for Custom Audiences to work on Facebook?
Facebook requires a minimum of 100 people for a Custom Audience to be targetable. However, audiences under 1,000 are too small for effective delivery. For Custom Audiences used as Lookalike seeds, aim for 1,000-5,000 people minimum. For retargeting campaigns, audiences of 5,000-50,000 typically provide the best balance of relevance and delivery.
How long do Custom Audiences take to populate?
Website Custom Audiences start populating immediately after the Meta Pixel fires. Customer list uploads typically take 30-60 minutes to match and become available. Engagement audiences (video viewers, page engagers) build gradually as interactions occur. New audiences may need 24-48 hours before ad delivery stabilizes.
Are Lookalike Audiences still effective after Apple’s iOS privacy changes?
iOS 14.5+ App Tracking Transparency reduced the data Facebook receives from iOS users, which affects Lookalike quality. Mitigations: implement Conversions API (CAPI) for server-side tracking, use phone-number-based customer lists (less affected than pixel-based audiences), increase Lookalike percentages slightly (3 % instead of 1 %), and combine Lookalikes with broad targeting to give Facebook’s algorithm more room.
How often should I refresh Custom Audiences and Lookalikes?
Website Custom Audiences refresh automatically based on the retention window you set. Customer lists should be re-uploaded monthly. Lookalike Audiences refresh automatically when the source audience changes. However, recreating Lookalikes quarterly from fresh customer data can improve performance as your customer profile evolves.
What is the typical CPA difference between interest targeting and Custom/Lookalike targeting in India?
Based on benchmarks from Indian campaigns: interest-based targeting CPA averages ₹200-₹500 for e-commerce and ₹500-₹2,000 for lead generation. Well-optimized Custom Audience retargeting reduces CPA by 50-70 % (₹100-₹200 for e-commerce). Lookalike prospecting typically delivers 20-40 % lower CPA than interest targeting (₹120-₹350 for e-commerce). Results vary significantly by industry, product, and creative quality.
