GA4 Attribution Models Explained

Which attribution models GA4 still offers

GA4 no longer offers the older first-click, linear, time-decay, or position-based models in standard attribution reporting. The models you typically compare today are data-driven and paid and organic last click. In some Google Ads contexts, Google paid channels last click is also relevant.

That matters because many older attribution articles still describe models that are no longer available in GA4. If your reporting playbook was written from theUniversal Analytics era, review it before using it as a governance standard.

The two lookback windows in GA4

• Acquisition key event lookback window: Applies tofirst_openandfirst_visit. The available options are 7 days or 30 days.
• Other key event lookback window: Applies to all other key events. The available options are 30 to 60, or 90 days.

Google's documentation notes that the selected key event lookback window also applies to session attribution. That is why session-based channel reporting can shift when teams change attribution settings, and why the difference betweenUser acquisition and Traffic acquisitionreports can suddenly look bigger.

How the lookback window changes the story

Imagine a user first visits via paid social, returns later through email, and converts weeks after the first session. If the relevant touchpoint falls outside the configured lookback window, it cannot receive credit in the attribution model, no matter how persuasive that first click was in reality.

This is why longer buying cycles often need longer review windows. It is not because GA4 becomes more truthful at 90 days by default. It is because the property is allowing more eligible touchpoints into the analysis.

Where teams misread attribution reports

One common mistake is comparing user-scoped or session-scoped traffic dimensions to event-scoped conversion reports as if they obey the same attribution logic. Google's documentation distinguishes these scopes. User-scoped and session-scoped dimensions use paid and organic last click, while event-scoped traffic dimensions reflect the property's selected reporting attribution model.

Another mistake is forcing GA4 to match an ad platform exactly. GA4 is useful for channel QA and cross-channel analysis, but it is still a separate measurement system with separate rules, identity constraints, and consent inputs — the same dynamic that makesGA4 and Google Ads numbers divergeby design. Consent gaps also feed intoconversion modelling, which adjusts attributed conversions when raw signals are missing.

Choosing settings that fit the business

• Short sales cycles often work with shorter windows because fewer materially relevant touches happen far from conversion.
• Longer B2B or considered-purchase journeys usually need a wider review window so earlier sessions remain eligible for credit.
• If your team reports heavily on assists and channel contribution, data-driven often gives a broader view than last click.
• If your team needs a simpler operational comparison, last click can be easier to explain, but it narrows the story — especially forpaid social channels like Metathat often appear earlier in the path than the converting touchpoint.