UTM and attribution windows
An attribution window is the time span within which a tagged touch can be credited for a conversion. Because UTM captures the touch but the window is set in the analytics tool, the same UTM-tagged click can receive credit in one report and not another. Understanding windows explains why campaign attribution varies across tools.
What a window decides
An attribution window is the maximum time between a tagged touch and a conversion for the touch to receive credit. A 7-day window credits the UTM-tagged click only if conversion happens within seven days; a 30-day window is more generous. The UTM itself does not carry a window — it records the touch, and the tool applies the window when crediting.
Different tools default to different windows and models (first-touch, last-touch, position-based), so the same tagged click can be credited differently across reports.
- Window = max time from touch to crediting a conversion
- UTM records the touch; the tool applies the window
- Tools differ in default windows and models
Reconciling across tools
When campaign numbers disagree, compare the windows and models before assuming a tagging problem. A tagged touch that falls just outside one tool's window appears uncredited there while showing up in a tool with a longer window.
Window defaults and configurability vary by platform, so specifics are described generally and this entry is partially verified. Note each tool's window when comparing UTM-attributed conversions, and reconcile against a window-independent record of the touch.
How it appears in analytics and logs
If a UTM-tagged campaign shows conversions in one tool but not another, differing attribution windows or models are a likely cause. The tagged touch is the same; what differs is how long after the touch a conversion still counts.
Diagnostic use case
Explain why a UTM-tagged campaign gets different conversion credit across tools, by recognising that each applies its own attribution window and model to the same tagged touch.
What WebmasterID can help detect
WebmasterID records the tagged touch server-side with its timestamp, giving a window-independent record of when the campaign click happened that you can compare against any tool's windowed attribution.
Common mistakes
- Assuming UTM carries an attribution window — the tool sets it.
- Comparing campaign conversions across tools without checking their windows.
- Reading a window mismatch as a broken UTM.
- Encoding identity into UTM to try to extend attribution.
Privacy and accuracy notes
Attribution windows operate on campaign touches and conversions, not personal identity. UTM values remain campaign metadata; do not encode a person to extend or join attribution.
Frequently asked questions
- Do UTM parameters set the attribution window?
- No. UTM records the campaign touch. The attribution window — how long after the touch a conversion still gets credit — is configured in the analytics tool, which is why the same tagged click can be credited differently across tools.
Related pages
- UTM limits for multi-touch attribution
UTM tags are excellent at labelling a click, but a customer journey has many touches and UTM only stamps the ones that pass through tagged links. This page is an honest account of the last-non-direct caveat and the limits of building multi-touch attribution on UTM alone.
- UTM vs first-party attribution
UTMs and first-party attribution solve overlapping but distinct problems. UTMs label the inbound link — which source, medium, and campaign brought someone in. First-party attribution uses your own data (logins, server sessions, consented identifiers) to connect touches into a journey. As third-party signals fade, the two are increasingly used together. This page covers how they complement each other and where each is strongest.
- UTM parameters and default channel grouping
Analytics tools sort traffic into channel groups (Paid Search, Organic Social, Email, Referral, Other) using rules built mostly on utm_medium. Choose the wrong medium and good traffic falls into 'Other' or the wrong channel. This page explains how the mapping works and the medium values that keep channels correct.
- Attribution analytics
Compare windowed credit against a record of the touch.
Sources and verification notes
- Google Analytics Help — Attribution and conversion windowsAttribution models and lookback windows applied to campaign touches.
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.