Two ways Google learns about a Shopify sale
Google Ads can get purchase data in two main ways. The first is the Google Ads conversion tag, usually installed through Shopify's Google & YouTube app, which fires in the browser when an order is placed. The second is Google Analytics 4: GA4 records the purchase, and you import that GA4 purchase into Google Ads as a conversion action.
Both work. The tag is direct and quick to set up. The GA4 route is useful when you want one source of truth for purchases. A third way is to upload each purchase straight to Google Ads from a server, as a click conversion. Settl sends to GA4 and can upload to Google Ads directly too.
Where Google Ads conversions get lost
- Ad blockers and privacy browsers that block Google's tags.
- Cookie banners: without consent, Google's tags run in a limited mode or not at all, depending on your consent setup.
- Buyers who click on mobile, then come back days later on another device or through another channel.
- Safari's limits on cookies, which shorten how long the click is remembered in the browser.
- Order status pages that never load because the buyer closed the tab after paying.
How server-side purchases reach Google
Settl saves the gclid (and Google's iOS click ids, gbraid and wbraid) when the visitor lands, and keeps it for 90 days. When Shopify reports a paid order, Settl sends a purchase event to your GA4 property through Google's Measurement Protocol, from the server. It carries the order id as transaction id, the value, currency, products, the saved gclid, hashed email, and consent signals from the visit. If you connect Google Ads, purchases from buyers who came from a Google ad are also uploaded straight to Google Ads as click conversions, with hashed email and phone (enhanced conversions) and the order id.
Use either the direct upload or the imported GA4 purchase as your Google Ads conversion. How many purchases Google can attribute to a specific ad click still depends on Google's own matching and on what the buyer allowed in your cookie banner.
Avoid double counting in Google Ads
The most common mistake is having two purchase conversion actions set as Primary, for example the Google Ads tag from the Google & YouTube app and an imported GA4 purchase, or an imported GA4 purchase next to Settl's direct upload. Google then counts each sale twice, and Smart Bidding chases a ROAS that doesn't exist.
Pick one purchase conversion action as Primary for bidding. Keep the other as Secondary if you want to compare them, or remove it. Within GA4 itself, the transaction id lets Google ignore repeat purchase events for the same order.
Google Ads conversion tracking on Shopify: what to optimize for
Good Google Ads conversion tracking on Shopify isn't only about counting purchases. It's about giving Smart Bidding the right signal. If you bid on Maximize conversion value or a target ROAS, Google needs the order value with every purchase, in the right currency, and it needs those purchases soon after they happen.
Keep micro-conversions like add to cart or begin checkout as Secondary. They're useful to watch, but if they're set as Primary, Google will happily find you people who add to cart and never buy.
Shopping and Performance Max campaigns rely heavily on this signal. When a part of your purchases never reaches Google, those campaigns underbid on the products and audiences that actually sell. Sending purchases server-side, with the click and the order id, is one of the simplest ways to give them a cleaner signal without touching the campaigns themselves.
How to check it works
In GA4, open the realtime report or DebugView after a test order and check that a purchase event with the right transaction id and value arrives. Then look at the Monetization reports after a day to compare the purchase count with your Shopify orders.
In Google Ads, go to Goals and then Conversions. Your purchase action should show a status like Recording conversions, with recent conversions listed. Imported GA4 conversions can take several hours to appear, so check the next day rather than right after a test order. The conversion diagnostics show issues like missing tags or low volume.