Ad platforms optimize toward the conversions they are told about. If tracking counts the wrong action, counts it twice or misses it, campaigns are optimized toward the wrong outcome and reports cannot be trusted. Conversion tracking is therefore the first thing to check before launching or restructuring Meta and Google Ads campaigns.
This checklist covers a typical setup for a lead generation or e-commerce website using Google Analytics 4, Google Ads and Meta. It assumes Google Tag Manager is used to manage tags, although the same principles apply to other setups.
Start with a tracking plan
Before configuring any platform, write down which actions matter to the business and how each one will be detected. A short tracking plan prevents most of the problems listed at the end of this article.
- The action, for example a submitted enquiry form, a booked call or a completed purchase.
- The trigger: a confirmed form submission, a thank-you page view or a server-side event.
- The event name used in every platform.
- Parameters to send, such as value, currency, form name or service.
- Which actions are primary conversions for bidding and which are secondary signals.
Use consistent naming conventions
Use lowercase names with underscores, and reuse Google's recommended event names where one fits, such as generate_lead or purchase. Use the same name for the same action across GA4, Google Ads and Meta's standard events, mapped in the tracking plan. Consistent names make reports comparable and make errors easier to spot.
GA4 key events
- Send each important action as a GA4 event with useful parameters.
- Mark only the events that represent business outcomes as key events. Page views and scrolls are rarely key events.
- Configure cross-domain measurement if the journey passes through another domain you control, such as a booking engine.
- Add payment providers and other third-party domains to the unwanted referrals list so they do not take credit for conversions.
- Register custom parameters as custom dimensions if you need them in reports.
Google Ads conversions
Conversions can be measured with the Google Ads tag or imported from GA4 key events. Either can work, but avoid having both set as primary for the same action, or the conversion will be counted twice in bidding.
- Keep auto-tagging enabled so the gclid is added to ad clicks, and check that redirects on your site do not remove it.
- Set the counting option per action: one conversion per click for leads, every conversion for purchases.
- Pass a value and currency where they are known, even as an estimate agreed with the business.
- Consider enhanced conversions, which send hashed customer data such as email address to improve matching.
- Mark only the conversions you want campaigns to optimize toward as primary.
Meta Pixel and the Conversions API
The Meta Pixel runs in the browser and can be blocked by browser settings, extensions or consent choices. The Conversions API sends the same events from your server. Running both gives Meta a more complete picture, but only if the duplicate events are recognized as one.
- Use Meta's standard events, such as Lead or Purchase, where they fit the action.
- Send the same event name and the same event ID from the Pixel and from the Conversions API. Meta uses this pair to deduplicate.
- Include customer information parameters, hashed where required, so that server events can be matched to people.
- Review the event match quality and deduplication status for each event in Events Manager.
Deduplication in practice
Generate one event ID when the action happens, for example when a form is submitted, and pass it to both the browser Pixel call and the server request. If the two IDs differ, Meta treats them as two separate conversions.
Consent mode
Where consent is required, tags must respect the visitor's choice. Google's consent mode passes that choice to Google tags through four signals: ad_storage, analytics_storage, ad_user_data and ad_personalization. Set default states before any tag fires, and update them when the visitor makes a choice in your consent banner.
Meta has its own consent controls for the Pixel, and server-side events should follow the same rules as browser events. Confirm which regulations apply to your audience before deciding how tags behave without consent.
Testing tools
- Google Tag Manager preview mode, to see which tags fire on each action.
- Google Tag Assistant, to inspect the tags and consent states on a page.
- GA4 DebugView, to confirm events and parameters arrive in the property.
- The conversion action status and diagnostics in Google Ads.
- Meta Pixel Helper, a browser extension, to check Pixel events on the page.
- Test Events in Meta Events Manager, to confirm both browser and server events and their deduplication.
Test every conversion end to end with a real submission or a test purchase, then check that it appears once in each platform.
Common errors
- Conversions firing when the form is viewed or the button is clicked, rather than when the submission succeeds.
- Thank-you pages that count again when they are refreshed or bookmarked.
- The same action counted by both a GA4 import and the Google Ads tag as primary conversions.
- Pixel and Conversions API events sent without matching event IDs.
- Payment or booking domains appearing as the source of conversions.
- UTM parameters added to internal links, which overwrite the original traffic source.
- Tags that never fire because consent defaults were set incorrectly.
- Expecting numbers to match exactly across platforms. Each platform uses its own attribution model and window, so totals will differ.
Keep it maintained
Tracking breaks quietly when websites change. Re-test conversions after site releases, form changes and new campaigns, and keep the tracking plan up to date so the next person can understand what each event means.
