

Dec 25, 2025
Setting Up Offline Conversions with GCLID: The Missing Link
Connect digital ads to valuable offline sales

Alex Ashcroft
Founder
Why Your Business Might Be Missing Half the Picture
I remember talking to a client last year who was convinced their Google Ads weren't working. Their online conversion metrics looked dismal, but when we dug deeper, we discovered something fascinating. Their most valuable customers were calling or visiting their showroom after clicking ads—actions completely invisible to standard tracking!
This is where Google Click ID (GCLID) comes into its own. It's the missing link that connects your digital advertising to those crucial offline conversions that many businesses rely on.
What's All This GCLID Business About?
Simply put, GCLID is a unique identifier Google attaches to your ads. When someone clicks, this code follows them to your website. The magic happens when you capture this code and connect it to whatever happens next—whether that's a phone call, in-store visit, or sales meeting weeks later.
The results can be transformative:
You'll see which campaigns actually drive sales, not just clicks
Google's algorithms get smarter about finding your ideal customers
Your budget flows to what's genuinely working, not what looks good on paper
You'll measure true return on ad spend, including offline revenue
Google reckons advertisers implementing this see about 30% better conversion rates. In my experience, that figure can be even higher for businesses with significant offline sales.
Getting Your Ducks in a Row
Before diving in, you'll need:
A Google Ads account with conversion tracking set up
Auto-tagging turned on in your account settings
The right permissions to create and edit conversions
Somewhere to store customer data (CRM, spreadsheet, etc.)
How to Capture Those Valuable GCLIDs
First: Turn On Auto-Tagging
Log into Google Ads
Go to Settings > Account Settings
Find "Auto-tagging"
Switch on "Tag the URLs I use for Google Ads campaigns"
Save changes
Next: Set Up Your Website to Grab the GCLID
You've got several options here:
The Hidden Form Field Approach
Add this to your lead forms:
Then use this JavaScript to populate it:
The Cookie Method (For Longer Sales Cycles)
Using Google Tag Manager
If you're already using GTM, you can:
Create a Custom JavaScript Variable for the GCLID
Set up a Cookie Variable to store it
Use a Custom HTML Tag to add it to forms
Store GCLID in Your Customer Database
This is crucial—you need to keep that GCLID linked to the customer:
If you use a CRM, create a custom GCLID field
For spreadsheet users, add a GCLID column
Custom database? Add a GCLID field to your schema
Setting Up Google Ads to Receive Offline Conversions
With GCLIDs being captured, tell Google what to look for:
In Google Ads, go to Tools & Settings > Measurement > Conversions
Click the blue plus button
Select "Import"
Choose "Other data sources or CRMs" then "Track conversions from clicks"
Configure your conversion:
Name it clearly (e.g., "Offline Sale")
Pick the right category
Set a value (or use variable values)
Decide whether to count every conversion or just one per click
Choose how long after a click to attribute conversions (up to 90 days)
Save your work
Getting Your Conversion Data Into Google
Now comes the part where you close the loop:
Create Your Import File
Make a CSV with these essential columns:
Google Click ID (the GCLID you captured)
Conversion Name (exactly matching what you created in Google Ads)
Conversion Time (when it happened, in YYYY-MM-DD HH:MM:SS format)
You can also add:
Conversion Value (how much money was involved)
Conversion Currency (if different from your account currency)
Attribution Credit (for partial attribution scenarios)
A simple example might look like:
Upload Your Data
In Google Ads, go to Tools & Settings > Measurement > Conversions
Find your offline conversion action
Click "Upload conversions"
Select your CSV file
Click "Apply"
You'll see any errors right away, and successful conversions will appear in your reports within a few hours.
Setting up offline conversion tracking isn't the simplest job, but it's genuinely worth the effort. I've seen businesses transform their marketing effectiveness once they connect these dots.
Keeping Things Running Smoothly
Data Hygiene Matters
Test your GCLID capture regularly to make sure it's working
Look for missing GCLIDs and figure out why they're not being captured
Be consistent with naming your conversions exactly as specified
Set a schedule for uploading data (weekly works for many businesses)
Level-Up Options
If you're handling loads of conversions, look into the Google Ads API
Many CRMs now offer direct Google Ads connections
Consider combining this with enhanced conversions for even better tracking
Mind the Privacy Bits
Update your privacy policy to mention this tracking
Under GDPR and similar regulations, you might need explicit consent
Decide how long you'll keep GCLID data and stick to it
Making It Worth the Effort
Once your offline conversion tracking is humming along:
Compare which campaigns drive online versus offline conversions
Try smart bidding strategies using your complete conversion data
Identify which campaigns bring in high-value customers
Refine your audience targeting based on who actually buys
The Bottom Line
For companies with significant offline sales, this isn't just a nice-to-have—it's essential. Without it, you're optimising in the dark, potentially cutting campaigns that drive your most valuable business.
The technical bits might seem fiddly at first, but once it's running, you'll wonder how you ever made decisions without seeing the complete picture. And your Google Ads performance? Well, that tends to improve dramatically when Google's algorithms can see what truly drives your business success.
