Primary and secondary conversions in Google Ads determine how Smart Bidding optimizes performance and which metrics are used to evaluate the actual results of your campaigns.

How do they work in Google Ads?

• Primary Conversion Action: Used for bid optimization and included in the "Conversions" column. Google Ads AI will target campaigns to get as many of these actions as possible within your budget.

In short, it is the event you are asking Google to replicate. If you are unsure whether to set an event as a primary conversion, ask yourself: Would I be okay with my entire budget going toward getting many events like this one?

• Secondary Conversion Action: Used strictly for observation and analysis. It appears only in the "All conversions" column. Google Ads will not use this data to adjust your bids, preventing the algorithm from optimizing toward low-value events.

Example 1: E-commerce Clothing Store in Google Ads

In a Google Shopping or Performance Max (PMax) campaign, the ultimate goal is Return on Ad Spend (ROAS).

It is recommended to choose this type of strategy because counting the number of sales isn't enough; it's about assigning higher value to orders with a higher average order value (AOV). Ideally, you should also import offline conversions to track returns, exchanges, repeat purchases, etc. The more reliable signals we feed Google, the better and more predictable the results will be.

Primary Conversion (for bid optimization):

• Purchase: The key event. It is configured with the monetary value of the transaction to enable strategies like Target ROAS (tROAS) or Maximize Conversion Value.

Secondary Conversions (for observation):

• Add to Cart: Allows you to see if ads are driving qualified traffic, but you don't want Google bidding to get "carts" instead of "purchases."
• Begin Checkout: Used to analyze what percentage of users drop off right before purchasing.
• Newsletter Subscription: Useful for measuring if Search campaigns are capturing traffic that registers before buying.

Note: These secondary conversions are often marked as primary when there isn't enough sales volume for Smart Bidding (around 30 per month) or when there are issues with tracking actual sales. However, keeping them secondary is the ideal setup.

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Example 2: Music School in Google Ads (Lead Generation)

In Search campaigns for lead generation (Lead Gen), the goal is to acquire high-quality contacts without wasting budget.

Primary Conversions (for bid optimization):

• Trial Class Request Form / Submitted Booking: The action that defines a high-value prospect. Configured using Target CPA (tCPA)—the maximum you are willing to pay per lead—or Maximize Conversions so Google targets similar profiles.
• Call from Ad or Website (> 60 seconds): A call lasting a certain duration shows a real intent to enroll.

Note: This is an estimate and depends on the specific business. For example, if selling online class packages were viable and recurring, setting that as a primary conversion would be a great idea.

Secondary Conversions (for observation):

• Click on WhatsApp Button: Shows engagement, but since it doesn't guarantee the user actually sent the message, it's best left as secondary to avoid biasing the algorithm.
• Click on Call Button (without connection established).
• Newsletter Signup.
• Pricing Dossier Download (PDF): Indicates interest, but optimizing bids toward PDF downloads might lead Google to target users who are just browsing prices.
• Visit to "Contact" or "Pricing" Page: Micro-conversions that confirm the quality of incoming traffic from keywords.

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Recommended Strategy

Always set the actions with the highest commercial value as primary to send a clear signal to the Smart Bidding algorithm. Keep interaction actions or intermediate funnel steps as secondary to use for remarketing audience creation and to assess the overall health of your ad funnel without miscalibrating your bids.

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