If you’re running Google Ads for your eCommerce store, there’s a good chance you’re wasting ad spend – and it’s not your fault.
Most ad accounts we audit before applying our Google Ads strategy have one common issue: their conversion settings are wrong.
Fixing this one setting can instantly help you:
- Lower your Cost per Acquisition (CPA)
- Increase your Return on Ad Spend (ROAS)
- Reduce wasted ad spend
- Improve profitability without spending more
Let’s break down exactly what to do.
1. The Problem: Multiple Primary Conversions = Confused Google Algorithm
When you go to your Google Ads account → Tools & Settings → Goals → Conversions, you’ll often see multiple conversions such as:
Purchases
Add to Cart
Begin Checkout
Page Views
At first, that might look fine – more data, right?
But the truth is: when all of these are set as Primary, Google optimizes for the wrong goals.
Instead of focusing on purchases (your real profit driver), Google starts optimizing for “page views” or “add to carts,” which don’t equal revenue.
2. The Fix: Set Only Purchases as Primary Conversion
Here’s what you need to do step by step:
Go to your Conversions tab.
Click on each non-purchase goal (like “Add to Cart,” “Begin Checkout,” or “Page View”).
Click Edit Settings → Conversion Action Optimization.
Change it from Primary to Secondary (not used for bidding).
By doing this, you’re telling Google:
“Use this data for insights, but don’t optimize my campaigns for these goals.”
Now, your ad campaigns will focus on generating real purchases, not just window-shoppers.
3. Why This Simple Change Matters for eCommerce
Google’s bidding algorithm learns from every conversion event.
If you mark “Page Views” or “Add to Carts” as Primary, you’re feeding Google bad signals.
That means it will look for cheaper traffic that adds to carts but doesn’t buy – killing your ROAS.
When you set only Purchases as Primary, Google focuses on buyers, not browsers.
You’ll notice:
Lower CPA
Higher conversion rate
Better audience signals
This small setting can make a massive impact on your profitability.
4. Check Your Conversion Value Settings
Inside the same settings menu, make sure your Purchase conversion tracks different values for each conversion – in your store currency (€, $, etc.).
Why this matters:
When you later switch from “Maximize Conversions” to “Maximize Conversion Value,” Google needs accurate sales values to calculate ROAS properly.
Without this, Google thinks all sales are worth the same – which is false for eCommerce stores.
5. Verify the Account Default Goal
Every campaign automatically uses your Account Default Goal unless told otherwise.
Go to Goals → Account Default Goals and make sure only Purchases are included.
If you see “Add to Cart” or “Page View” labeled as Account Default Goals – uncheck them.
Otherwise, Google will still use those as optimization signals across your campaigns.
