Primary vs Secondary Conversions in Google Ads: What’s the Difference and Why It Matters
When setting up conversion tracking in Google Ads, one of the most important — and often misunderstood — settings is Action Optimisation. Inside your conversions dashboard, you’ll notice that some conversions are marked as Primary while others are marked as Secondary.
At first glance, this might seem like a simple organisational feature. However, the difference between primary and secondary conversions can dramatically affect how your campaigns optimise, spend budget, and generate results.
In this guide, we’ll explain:
- What primary conversions are
- What secondary conversions are
- How smart bidding uses conversion data
- When to use each conversion type
- A real-world example of primary vs secondary conversions in action
What Are Primary Conversions in Google Ads?
Primary conversions are the main actions you want users to take on your website.
These are the conversions that matter most to your business goals and, importantly, they are the conversions Google Ads uses for Smart Bidding optimisation.
For example:
- Lead form submissions
- Phone calls
- Purchases
- Booking requests
- Demo requests
If your business relies on customers filling in a contact form, then that form submission should almost certainly be set as a primary conversion.
Why Primary Conversions Matter for Smart Bidding
The real importance of primary conversions goes beyond reporting.
If you use Smart Bidding strategies such as:
- Target CPA
- Maximise Conversions
- Target ROAS
- Maximise Conversion Value
Google uses your primary conversion data to decide:
- Who to show ads to
- How much to bid
- Which audiences are more likely to convert
- When to enter auctions
In other words, Google actively optimises your campaigns around these conversion signals.
So if you accidentally optimise for the wrong action, Google may start prioritising low-quality users who perform that action more frequently.
What Are Secondary Conversions?
Secondary conversions are actions you still want to measure, but do not want Google to optimise towards.
These conversions remain visible in reporting but are excluded from Smart Bidding optimisation.
That means Google records the action, but ignores it when making bidding decisions.
Why Secondary Conversions Are Useful
Many websites have multiple user interactions that provide useful insights, but are not strong enough to be treated as true business outcomes.
Examples include:
- Email link clicks
- PDF downloads
- Time on site milestones
- Video views
- Multi-step form progression
- Add-to-cart actions
- Newsletter signups
These interactions can still provide valuable behavioural data without influencing campaign optimisation.
Example: Email Link Clicks
Imagine your website contains a clickable email address.
A user clicks the link, opening their email application.
Technically, Google Ads can track the click itself — but it cannot confirm whether the user actually sent the email.
This creates a “soft” conversion signal.
If you allowed Smart Bidding to optimise heavily around email link clicks, Google might prioritise users who casually click email addresses rather than users who genuinely become customers.
That’s why this type of interaction works perfectly as a secondary conversion.
You still gain reporting visibility without risking poor optimisation decisions.
Primary vs Secondary Conversions: The Key Difference
Here’s the simplest way to think about it:
| Conversion Type | Used in Reporting | Used for Smart Bidding |
|---|---|---|
| Primary | Yes | Yes |
| Secondary | Yes | No |
Primary conversions influence optimisation.
Secondary conversions are purely informational.
When Should You Use Primary Conversions?
You should use primary conversions for actions that directly represent business success.
These are typically:
Lead Generation Businesses
- Contact form submissions
- Qualified leads
- Phone enquiries
Ecommerce Businesses
- Purchases
- Revenue generation
- Subscription signups
Service Businesses
- Appointment bookings
- Consultation requests
- Quote requests
If the action directly contributes to revenue or customer acquisition, it should normally be primary.
When Should You Use Secondary Conversions?
Secondary conversions work best for supporting actions or micro-conversions.
These include:
Engagement Signals
- Scroll depth
- Video plays
- Time on page
Research Behaviour
- PDF downloads
- Brochure requests
- Resource views
Funnel Tracking
- Multi-step form progression
- Add-to-cart actions
- Checkout starts
Communication Signals
- Email link clicks
- WhatsApp clicks
- Live chat opens
These actions help you understand user behaviour without allowing Google to over-optimise around weaker signals.
A Real-World Example of Primary and Secondary Conversions
One particularly effective use case involves combining:
- A secondary lead submission conversion
- A primary qualified lead conversion
Here’s how it works.
Step 1: Track All Lead Form Submissions
Initially, every form submission is tracked as a conversion.
This tells you how many leads are being generated overall.
However, not every lead is valuable.
Some may be:
- Spam
- Low quality
- Irrelevant enquiries
- Unqualified prospects
Optimising purely for form submissions can therefore lead to poor lead quality.
Step 2: Import Qualified Leads from the CRM
A better approach is to connect your CRM to Google Ads using offline conversion tracking.
Once connected, you can send back:
- Qualified leads
- Closed sales
- Revenue data
- Customer values
This creates a much stronger optimisation signal.
Google can now optimise towards actual business outcomes rather than simple form submissions.
Step 3: Set Form Submissions as Secondary
The original lead form conversion becomes secondary.
This means:
- You still see total enquiry volume
- Reporting remains intact
- Google no longer optimises for low-quality submissions
Step 4: Set Qualified Leads as Primary
Your CRM-imported qualified leads become the primary conversion.
Now Google Ads optimises towards:
- Better lead quality
- Higher-value customers
- Actual sales outcomes
This is one of the most powerful ways to improve Smart Bidding performance.
Understanding “Conversions” vs “All Conversions”
Inside Google Ads reporting, there are two important columns:
Conversions
This column only includes primary conversions.
These are the conversions Google uses for bidding optimisation.
All Conversions
This column includes:
- Primary conversions
- Secondary conversions
This gives a fuller picture of user activity and engagement.
Why the Difference Matters
Imagine your reports show:
- 3 primary conversions
- 10 total conversions
This might indicate:
- 3 qualified leads
- 7 softer engagement actions
Without separating primary and secondary conversions, Google may incorrectly optimise towards the easier actions instead of the valuable ones.
That can lead to:
- Lower lead quality
- Wasted budget
- Poor campaign efficiency
Best Practices for Conversion Setup
To get the best results from Google Ads, follow these guidelines:
Use Primary Conversions for Revenue-Critical Actions
Only include actions that genuinely represent success.
Keep Soft Signals as Secondary
Track engagement data without affecting optimisation.
Import Offline Conversions Where Possible
CRM integration and offline conversion tracking can dramatically improve lead quality optimisation.
Review Conversion Settings Regularly
As your business evolves, your conversion priorities may change.
Audit your setup periodically to ensure Smart Bidding is optimising towards the right outcomes.
Final Thoughts
Primary and secondary conversions are far more than simple labels inside Google Ads.
They directly influence how Google’s machine learning understands success in your account.
Getting this wrong can result in campaigns optimising towards weak signals that generate activity but not revenue.
Getting it right allows Smart Bidding to focus on the actions that truly matter to your business.
The best approach is usually:
- Primary conversions for real business outcomes
- Secondary conversions for supporting behavioural insights
When used correctly, this setup provides the perfect balance between optimisation accuracy and reporting visibility.
