Offline conversion import
Offline conversion import (OCI) connects events that happen away from the website — a sales call that closes, an in-store purchase, a qualified lead in a CRM — back to the online ad click that began the journey. It works by capturing a click identifier (such as Google's GCLID) at the start and later uploading the offline outcome keyed to that identifier, closing the online-to-offline attribution loop.
What this means
Many valuable conversions never happen in the browser: a B2B deal closes weeks later in the CRM, a shopper buys in a physical store, a lead qualifies after a phone call. Offline conversion import re-attaches those outcomes to the online click that started them.
The mechanism is a click identifier. When a user arrives from an ad, the platform appends an identifier (Google Ads uses GCLID; other platforms have equivalents). You store that identifier with the lead, and when the offline outcome occurs you upload a record — identifier plus conversion type, time, and value — so the platform credits the original click.
What it depends on
OCI only works if the click identifier is captured and preserved through the offline process. If the GCLID is dropped at form submission, lost in the CRM, or never stored, the offline outcome cannot be matched and the online channel gets no credit for revenue it actually drove.
The upload also has timing constraints — conversions must be imported within the platform's allowed window relative to the click — and value/time accuracy matters because that data flows straight into bidding and reporting. The platform's documentation defines the exact identifiers, fields, and windows.
- Capture a click identifier (e.g. GCLID) on arrival
- Store it with the lead through the offline process
- Upload the outcome keyed to the identifier within the window
How it appears in analytics and logs
Conversions that appear well after the click and reference offline outcomes indicate OCI; the link relies on a stored click identifier, so missing identifiers leave offline value unattributed.
Diagnostic use case
Use offline conversion import to attribute revenue that closes off-site — phone sales, in-store, CRM deals — back to the originating online interaction instead of losing it from reports.
What WebmasterID can help detect
WebmasterID captures first-party landing context and campaign parameters, which helps you preserve the click-identifier and source data an offline-import workflow depends on.
Common mistakes
- Dropping the click identifier between the landing page and the CRM.
- Importing conversions outside the platform's allowed window.
- Uploading inaccurate values that distort bidding and reports.
Privacy and accuracy notes
OCI matches an offline outcome to a click via an identifier you captured with consent; it is a first-party data flow you control. This is educational, not legal advice — confirm consent obligations with counsel.
Related pages
- Enhanced conversions
Enhanced conversions is a Google Ads feature that supplements cookie-based conversion measurement by sending hashed first-party customer data — such as an email address the user provided — to match conversions that cookies alone would miss. The data is hashed (SHA-256) before transmission. It is one industry response to the decline of third-party identifiers, with its own consent and configuration requirements.
- Conversion lag (time-to-conversion)
Conversion lag is the time between an interaction and the resulting conversion. Some conversions happen minutes after a click; others take days or weeks. Because of lag, recent activity always looks under-performing at first — conversions for recent touches have not happened yet — and the lookback window must be long enough to capture them. It is a core reason attribution reports change as data matures.
- Cross-channel attribution
Cross-channel attribution distributes conversion credit across all the channels a user touched — paid search, organic, social, email, referral, direct — rather than crediting only what one platform can observe. It is the antidote to siloed, self-reported platform counts: by viewing the whole path in one place, it can apportion credit coherently and reveal how channels actually work together.
- Campaign links
Preserve campaign and click context through the journey.
Sources and verification notes
- Google Ads Help — About offline conversion importsDocuments GCLID-keyed offline conversion import and upload windows.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.