How to Set Up Google Ads Conversion Tracking with GTM (Step by Step)

Most Google Ads accounts I audit have conversion tracking "set up", yet the numbers do not match the leads or sales the business received. A tag fires on the wrong page, a purchase counts twice, or a button click is treated as a lead, and Smart Bidding optimises toward the wrong thing.

In this guide I walk through how I set up Google Ads conversion tracking with Google Tag Manager (GTM), from creating the conversion action to testing it, plus the settings that decide whether your numbers can be trusted.

What do you need before you start?

You need edit access to your Google Ads account, a GTM container installed on every page of your website, and a clear list of the actions that count as real business results. Getting that list right matters more than any tag setting.

Before touching GTM, write down:

• Your primary conversions: the outcomes you want to pay for, such as purchases, quote requests, booking forms or calls from the website.
• Your secondary actions: useful signals you want to observe but not bid on, such as a pricing page view or a WhatsApp click.
• Where each action happens: a thank-you page, a form submit event or a checkout confirmation.
• Whether a value applies: a real order value, or an estimated lead value.

If you are unsure whether your existing GTM container is healthy, my post on Google Tag Manager mistakes that break conversion tracking covers the usual problems.

How do you create a conversion action in Google Ads?

You create a conversion action in the Goals section of Google Ads, usually under Goals > Conversions, by choosing a website conversion and setting it up manually so you get a Conversion ID and Conversion Label for GTM. Google moves these menus from time to time, so look for "New conversion action" in the Goals area if the path looks different.

1. Open Goals > Conversions and start a new conversion action.
2. Choose Website as the source. I prefer manual setup over Google's automatic event suggestions.
3. Pick a goal category that matches the action, such as Purchase, Submit lead form or Book appointment.
4. Set the value: use different values for each conversion (ecommerce), the same value for each conversion, or no value.
5. Choose the count setting (explained below).
6. Review the attribution settings and click-through window.
7. Save, then choose the option to set it up with Google Tag Manager. Copy the Conversion ID and Conversion Label.

Which conversion settings matter most?

Three settings shape how the conversion behaves in reporting and bidding: primary versus secondary, the count setting, and the attribution model.

Primary actions appear in the "Conversions" column and are used by bidding when they belong to the goals a campaign optimises for. Secondary actions are recorded in "All conversions" for observation only.

Count "One" records at most one conversion per ad interaction, which suits leads, because one person submitting a form three times is still one lead. Count "Every" suits purchases, where each order matters.

On attribution, data-driven attribution is the default and spreads credit across ad interactions based on your account's data. Last click is still available. The older rule-based models such as first click and linear have been retired.

How do you add the Google tag and conversion linker in GTM?

You need a Google tag for your Google Ads account (the AW- ID) or a Conversion Linker tag firing on all pages, so the click identifier from the ad is stored in first-party cookies and available when the conversion happens. Without that, conversions are often missed or attributed poorly.

The click identifier is the GCLID (Google Click Identifier), a URL parameter Google adds when someone clicks your ad.

In practice I set up both:

1. Google tag: create a Google tag with your Google Ads tag ID (AW-XXXXXXXXX) and fire it on Initialization - All Pages. GTM now encourages this, and the Google tag handles linking and supports features like enhanced conversions.
2. Conversion Linker: add a Conversion Linker tag on All Pages. It does no harm alongside the Google tag and covers containers where the Google tag is missing or blocked by consent settings.

If you use Consent Mode v2, these tags respect the consent state. Read my guide to Consent Mode v2 if you serve visitors in regions that require consent banners.

How do you create the Google Ads conversion tag in GTM?

You create a Google Ads Conversion Tracking tag in GTM, paste the Conversion ID and Label, map value and currency, and fire it on a trigger that only runs when the conversion genuinely succeeds.

Step 1: Push the conversion to the data layer

The most reliable trigger is a custom event your website pushes after a successful form submit or order. For a purchase it looks like this:

window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  event: 'purchase',
  ecommerce: {
    transaction_id: 'ORD-10452',
    value: 2450,
    currency: 'BDT'
  }
});

For a lead, a simple event: 'generate_lead' push after the form's success response is enough.

Step 2: Create variables and the trigger

1. Create Data Layer Variables for ecommerce.transaction_id, ecommerce.value and ecommerce.currency.
2. Create a Custom Event trigger matching the event name (purchase or generate_lead).

Step 3: Configure the tag

1. Add a new tag of type Google Ads Conversion Tracking.
2. Paste the Conversion ID and Conversion Label.
3. Map Conversion Value, Transaction ID and Currency Code to your variables.
4. Attach the custom event trigger and save.

The transaction ID matters because Google Ads uses it to ignore duplicate conversions with the same ID, which protects you when a customer reloads the order confirmation page.

What if you only have a thank-you page?

A Page View trigger on the thank-you URL works but is weaker: anyone who revisits that page triggers a conversion. If you must use it, match the exact path and set the count to "One".

How do you test Google Ads conversion tracking?

You test by running GTM Preview mode with Tag Assistant, completing a real conversion, and confirming the conversion tag fired once with the right values. Then you check the conversion action's status in Google Ads over the following days.

My testing checklist:

• The Google tag or Conversion Linker fires on every page view
• The conversion tag fires only on the success event, not on a button click
• It fires once per conversion, not twice
• Value, currency and transaction ID are populated, not "undefined"
• A test visit with a ?gclid=test parameter results in a _gcl_aw cookie being set
• The container is published, not just saved in a workspace
• The conversion action status in Google Ads updates within a day or so

Should you import GA4 conversions instead?

You can import GA4 key events into Google Ads, but for primary bidding conversions I generally prefer native Google Ads conversion tags. Native tags give you direct control over count and value.

A common, sensible setup is native Google Ads tags as primary and GA4 imports as secondary for comparison. Never set the same action as primary from both sources, or Google Ads will count it twice. If the two sources disagree, my post on why GA4 and Google Ads show different conversion numbers explains the usual reasons.

What should you add after the basic setup?

Once the basic tag works, add enhanced conversions and, for lead businesses, offline conversion imports. These close the gaps that browser-only tracking leaves.

• Enhanced conversions send hashed email or phone data with the conversion, so Google can match more conversions to ad clicks.
• Offline conversions send qualified leads or closed deals from your CRM back to Google Ads.
• Call tracking covers phone leads, which matter a lot for service businesses.

This is the same layered approach I used for TalkBar, where GTM became the central tracking hub and Google Ads conversion actions were created for calls, reservations and form submissions, with enhanced conversions on top.

Final thoughts

Good conversion tracking is less about the tag and more about deciding which actions really count, then making sure each one fires once, with the right value, on genuine success. If you want this built and tested properly, see my advanced conversion tracking service or book a free tracking audit.