Offline conversions are valuable actions that happen away from your website or app, such as a phone sale, a booked appointment, an in-store purchase or a lead that your sales team marks as qualified, and which you report back to Meta. Sending them lets Meta measure which ads led to real business and steer delivery towards similar people.
How offline conversions work
The principle is matching. When someone fills in a lead form, calls you or buys in person, you record identifying details such as their email address or phone number. Later you send Meta an event, for example “Purchase, £450, 12 September”, with those identifiers. Before they leave your system they are converted with hashing, a one-way code, and Meta compares the hashes with its own users to see who had seen or clicked your ads.
Meta used to run a separate Offline Conversions API and offline event sets. At the time of writing (October 2026) it has retired those and moved offline events onto the Conversions API, so offline and website events live in the same dataset with an action source showing where each happened. You can send them by uploading a file in Events Manager, through a direct Conversions API connection, or through a built-in integration with your CRM.
For lead ads, the CRM route allows Meta to optimise for leads that progress to a chosen stage, such as “qualified” or “won”, rather than for every form submission.
Why it matters
Many UK businesses close the sale offline. A kitchen fitter takes an enquiry online and wins the job after a home visit. A private clinic books a consultation by phone. A car dealer sells on the forecourt. Without offline conversions, Meta sees only the first step and keeps finding people who fill in forms, not people who buy. Feeding back the outcome is often one of the most effective ways to improve lead quality.
There is a UK GDPR side. Hashed emails and phone numbers are still personal data, because they can be matched back to a person. You need a lawful basis for sharing them with Meta, your privacy notice should say that you do, and you should not send data for anyone who has objected to marketing use. Take advice if you are unsure which lawful basis applies.
Common mistakes
- Collecting no email or phone number at the point of sale, so there is nothing to match.
- Formatting phone numbers inconsistently. UK numbers should include the country code, such as 447700900123, before hashing.
- Uploading events weeks late or in irregular batches, which weakens both reporting and optimisation.
- Counting the same sale through the website pixel and an offline upload without deduplication.
- Sending every lead as a conversion, rather than only those that reached a meaningful stage.
How to act on it
List the offline outcomes that matter, then check your CRM or till system records an email or phone number for each one. Choose the simplest reliable route: a native CRM integration if your system has one, otherwise a scheduled Conversions API connection, with manual file uploads only as a stopgap. Watch the match quality score in Events Manager and fix formatting problems it reports.
Update your privacy notice before you start. Closing the loop between ads and sales is central to how I run Facebook lead ads, and the event match quality entry explains how to read the score that tells you whether matching is working.