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Google Analytics Offline Conversions: Track Sales & Converted Leads with GA4

Learn how to track offline conversions in Google Analytics 4 (GA4). Discover the Measurement Protocol, BigQuery and Octanist to connect CRM sales data, attribute offline revenue, and improve campaign reporting.

Google Analytics Offline Conversions: How to Track Revenue and Converted Leads Beyond Your Website

Most businesses today rely on Google Analytics to measure website conversions such as form submissions, purchases, quote requests, or downloads. But what if a large part of your customer journey happens offline?
Think of phone calls, in-store visits, signed contracts, or invoices. These valuable actions often go untracked in Analytics, meaning critical offline revenue data never makes it back into your reports.
The solution? Offline conversion tracking in Google Analytics.

What Offline Data Can Be Uploaded to GA4?

Google Analytics 4 (GA4) allows you to import different types of offline data:
  • Cost Data Import advertising cost data from non-Google sources. This links cost to campaigns, sources, and media in reporting.
  • Item Data Upload product metadata such as brand, category, and variant. GA4 will use this to correct or enrich historical reports.
  • User Data (per User-ID) Import User-ID data from your CRM to update user properties. These can be used for GA4 audiences and analysis.
  • User Data (per Client-ID or App-Instance-ID) Upload identifiers to connect CRM data back to GA4 sessions and users.
  • Event Data Import events that weren’t collected in real time (for example, from offline sources).
  • Custom Event Data Add extra metadata to events via custom dimensions to expand or correct existing reporting.
To learn more about importing offline events, please refer to the GA4 Import Events page.
Beyond the standard uploads, you can also send your own CRM data directly to GA4 using the Measurement Protocol.

Sending Offline Data with the GA4 Measurement Protocol

The Measurement Protocol is a server-to-server method that allows you to send events directly to GA4. This is especially useful for:
  • A signed contract that is recorded in your CRM
  • An invoice that is paid offline
  • An order fulfilled in your ERP system instead of your webshop
To implement the Measurement Protocol, you’ll need:
  • Client ID or Session ID (collected during the user’s online session)
  • API Secret created in GA4
This ensures offline conversions are linked back to the correct user and marketing channel.

Using BigQuery for Offline Conversion Tracking

Another way to connect offline conversions with your Google Analytics data is by using BigQuery. When you link GA4 to BigQuery, all of your online event data is exported to a raw database. From there, you can enrich it with offline information from your CRM, POS system, or call center.
For example:
  • A lead comes in through your website and is logged in GA4
  • Weeks later, your sales team closes the deal in the CRM
  • By uploading that offline revenue into BigQuery, you can stitch the two data sources together
This approach allows you to create a single view of the customer journey, showing how online interactions ultimately drive offline sales.
The advantage of BigQuery is flexibility: you can run detailed queries, build advanced reports, and use the data for long-term storage and analysis. The drawback is that offline conversions stitched in BigQuery do not flow back into GA4’s standard reports, they only live in BigQuery itself.
Still, for businesses that want deep insights and full control over their data, BigQuery is a powerful option to unify online and offline conversion tracking.

How Can You Send Offline Data Back to GA4?

There are four main methods:
  1. Manual Uploads (CSV files)
  2. GA4 Measurement Protocol (server-to-server)
  3. Combining data using Google BigQuery
  4. Third-party tools like Octanist

The Main Challenge with Offline Conversion Tracking

The hardest part of offline conversion tracking in Google Analytics is collecting the correct identifiers (Session ID or Client ID) in your CRM.
Without them:
  • GA4 may reject your event
  • Or GA4 records the conversion but can’t attribute it to a channel, campaign, or user
This results in incomplete reporting: you see the totals but not where the conversions came from.

How Octanist Solves This

Octanist automatically collects the necessary identifiers (Session ID and Client ID) whenever a user fills out a form, requests a quote, or takes another action on your website.
Later, when that lead converts offline, by visiting your store, closing a deal, or purchasing after follow-up, Octanist sends that data back into GA4 (and optionally to Google Ads, LinkedIn, Microsoft Ads, etc.).
This way:
  • Online behavior is tied to offline actions
  • Offline events are sent back securely via the GA4 Measurement Protocol
  • Conversions are attributed to the right channels
If you want even more control over your data, you can connect Google BigQuery with Octanist. This allows you to combine your GA4 event data with sales data from your CRM, enrich it with offline conversions, and then send the results back into Google Analytics 4 for complete reporting.
With Octanist, offline revenue and lead conversions become part of your complete marketing reporting.

Next Steps

Want to connect your offline conversions with Google Analytics 4?
  • Read our GA4 documentation for detailed setup instructions
  • Or contact us at support@octanist.com