A secondary conversion is a conversion action in Google Ads that is tracked and reported, but not counted in the main Conversions column and not used to steer automated bidding. It sits in the All conversions column, so you can watch it without telling Google to chase it.
How a secondary conversion works
Every conversion action in Google Ads has an optimisation setting of either primary or secondary. A primary conversion counts in the Conversions column and feeds bid strategies such as Maximise conversions and Target CPA. A secondary conversion counts only in All conversions and the related value columns, and bidding ignores it.
Primary and secondary work within conversion goals, which group actions by category, such as purchases, leads or sign-ups. The account-default goals apply to every campaign unless you set campaign-specific goals. One detail catches people out: if you add a goal containing a secondary action to a campaign as a campaign-specific goal, Google treats that action as primary for that campaign. The label is not absolute.
Typical secondary actions are the steps before an enquiry or sale: newsletter sign-ups, brochure downloads, clicks on a phone number, visits to a pricing page, or GA4 conversions imported from a linked property that duplicate a native Google Ads tag.
Why it matters
Smart bidding optimises towards whatever you count as a conversion. If a London architecture practice counts both “contact form submitted” and “portfolio PDF downloaded” as primary, Google will happily find cheap PDF downloads and report a falling cost per conversion while real enquiries dry up. Setting the download as secondary keeps it visible without distorting the bidding.
Secondary conversions also prevent double counting. Many UK accounts track the same purchase twice, once through the Google tag and once through a GA4 import. Leaving both as primary inflates results and confuses bidding; making one secondary fixes that while keeping the second as a cross-check.
Common mistakes
- Leaving every action primary, including page views and micro-actions, so bidding chases the easiest one.
- Importing GA4 key events as primary alongside the matching Google Ads tag, doubling the count.
- Setting an action to secondary, then adding it to a campaign-specific goal and wondering why bidding chases it.
- Reading the All conversions column as if it were the Conversions column in reports to clients or managers.
How to act on it
Open the conversions summary in Google Ads and list every action. For each, ask one question: is this the outcome I would pay for? If yes, it is primary. If it is a useful signal or a duplicate, set it to secondary. A lead-generation account rarely needs more than one to three primary actions and several secondary ones; see macro conversions for how to choose the outcomes that matter.
Before you change any action to secondary, compare the numbers: if an action you are about to make secondary is the one most of your recorded conversions come from, your reported cost per conversion will rise overnight. That is the account telling the truth for the first time, not getting worse, so warn anyone who reads the reports before you make the change.
Then check each campaign’s goals to confirm it uses the account defaults or a deliberate campaign-specific goal. After any change, expect Smart Bidding to recalibrate for a week or two. Cleaning up conversion settings like this is often the first job when I take on an account through my PPC management service.