Cet article fait partie du guide Optimisation Google Ads : 10 Leviers Pour Ameliorer Vos Resultats
Without conversion tracking, Google Ads is a shot in the dark. You know how much you're spending. You know how many clicks you're getting. But you don't know which ones generate customers. And without that information, Google's algorithm can't optimize your campaigns.
70% of the Google Ads accounts we audit have incomplete or misconfigured tracking. It's the number one problem — before ads, before keywords, before budget.
Why Conversion Tracking Is Non-Negotiable
Google Ads uses conversion data to:
- Optimize bids — Smart Bidding strategies (Target CPA, Target ROAS, Maximize Conversions) need data to function
- Identify profitable keywords — without tracking, it's impossible to tell which keywords generate leads vs. junk traffic
- Feed the machine learning — the more conversion data Google has, the better it targets users likely to convert
Without tracking, you're using Google Ads in 2010-era manual mode. With tracking, you're leveraging Google's AI to optimize in real time.
Types of Conversions to Track
Primary Conversions (Business Actions)
These are actions that represent a real lead or sale:
- Contact or quote form submission
- Phone call (via call extension or click-to-call)
- Online purchase (e-commerce)
- Appointment booking
Secondary Conversions (Engagement Signals)
Actions that indicate interest without being a business conversion:
- Visit to a key page (pricing page, contact page)
- Time on site > 2 minutes
- Scroll > 75% of the page
- Document download
Primary conversions drive your bids. Secondary conversions inform your analysis.
Method 1: Installation via Google Tag (gtag.js)
The most direct method. You place the Google Tag code directly in your site's source code.
Step 1: Create the Conversion Action
- In Google Ads, go to Tools > Conversions
- Click "+ New conversion action"
- Select "Website"
- Define the name, category (Lead, Purchase, etc.), and value
- Choose the attribution model (data-driven recommended)
Step 2: Install the Global Tag
Place the Google Tag in the <head> of every page on your site. This tag loads the tracking library and sends basic data to Google.
Step 3: Configure the Conversion Event
For a form, trigger the conversion event on the thank-you page or via a JavaScript callback after submission.
For a phone call, use Google's call tracking snippet that dynamically replaces your number with a Google forwarding number.
Method 2: Installation via Google Tag Manager (Recommended)
Google Tag Manager (GTM) is the recommended method for sites with multiple tracking tags. It offers more flexibility and doesn't require modifying source code for every change.
Step 1: Install the GTM Container
Place the GTM container code in the <head> and <body> of your site. This is the only code change needed — everything else is managed in the GTM interface.
Step 2: Set Up the Conversion Linker Tag
Create a "Google Ads Conversion Linker" tag that fires on all pages. This tag ensures the GCLID (Google Click Identifier) is passed between the click and the conversion.
Step 3: Create the Conversion Tag
- New tag > Google Ads Conversion Tracking
- Enter the conversion ID and label (provided by Google Ads)
- Set the trigger: form submitted, thank-you page, custom event
Step 4: Test
Use GTM Preview mode to verify the tag fires correctly. Then check in Google Ads that conversions are appearing (24–48 hour delay).
Offline Conversions: Connecting Your CRM
This is where most advertisers stop — and it's where the real optimization begins.
Online tracking tells you a form was submitted. But did that lead become a customer? How much revenue did they generate? Without this information, Google optimizes for form submissions, not customers.
How It Works
- When a user clicks your ad, Google generates a GCLID (Google Click Identifier)
- You store this GCLID along with the lead's data in your CRM
- When the lead becomes a customer (or reaches a key pipeline stage), you send the GCLID back to Google with the conversion value
Import Methods
- Manual upload — CSV file in Google Ads (viable for small volumes)
- Automatic API import — direct connection between your CRM and Google Ads
- Via Zapier/Make — for CRMs without a native connector
- Salesforce/HubSpot — native connectors available
Importing offline conversions is what separates mediocre accounts from high-performing ones. It's the most powerful Google Ads optimization lever available.
Enhanced Conversions: The Answer to a Cookieless World
With the gradual disappearance of third-party cookies and tracking restrictions (iOS, browsers, ad blockers), a portion of conversions is no longer properly attributed. Enhanced Conversions solve this problem.
The principle: in addition to the GCLID, you send hashed first-party data (email, phone, address) that allows Google to match the click to the conversion even without a cookie.
Result: 5 to 15% more attributed conversions. This isn't extra traffic — it's conversions that already existed but Google couldn't see.
Consent Mode: Tracking Without Violating Privacy Laws
In regulated markets, you must obtain user consent before placing tracking cookies. Google Ads Consent Mode allows you to continue collecting anonymized signals even when the user declines cookies.
Proper Consent Mode configuration is essential to:
- Stay compliant with GDPR, CCPA, and other privacy regulations
- Not lose all your conversion data when 30–60% of users decline cookies
- Allow Google to model the missing conversions
The Most Common Tracking Mistakes
1. Double-Counting Conversions
A form that redirects to a reloadable thank-you page = a conversion counted every time someone visits that page. Solution: use a trigger based on the submission event, not the page.
2. Conversions Without Values
If all your conversions have the same value (or no value), Google can't distinguish a $100 lead from a $10,000 lead. Assign different values to each conversion type.
3. Attribution Window Too Short
The default window is 30 days. If your B2B sales cycle is 90 days, you're missing conversions. Adjust the window to match your cycle.
4. No Regular Testing
Tags break. A site update, a CMS change, a new cookie banner — and tracking stops without you knowing. Test every month.
Verification Checklist
- The Google Tag (or GTM) is present on all pages
- The Conversion Linker is active
- Primary conversion actions are configured with the correct values
- The attribution model is "Data-driven" (not "Last click")
- Consent Mode is configured for visitors in regulated markets
- Enhanced Conversions are active
- The tag fires correctly (verified in Preview mode)
- Conversions are appearing in Google Ads (checked after 48h)
- Offline conversion import is in place (if applicable)
- Monthly testing is scheduled
Tracking as a Competitive Advantage
Most of your competitors track form submissions and stop there. If you track all the way to the signed customer via offline conversions, you're giving Google signals that your competitors aren't. The algorithm optimizes on data that's closer to actual business outcomes.
It's an invisible but massive advantage. It translates directly into your ROAS and every Google Ads KPI you track.
Is your tracking reliable? Book a free consultation — we'll verify your setup from end to end and identify the conversions you're not seeing.
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