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Google Ads Attribution Models: Data-Driven vs Last Click

Only two models remain. Here’s how each splits the credit, which to choose, and how to compare them on your own data before you switch.

VDBy Vikas Disale·7 min read
Quick answer

An attribution model decides how conversion credit is split across the ad clicks on the path to a sale. In 2026 only two remain: Data-Driven (AI spreads credit across touchpoints — the default and recommended) and Last Click (100% to the final click). The four rules-based models were retired in 2023. For most advertisers, data-driven is the right choice; use the Model Comparison report to see the difference on your data before switching.

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2026 noteOnly two attribution models remain: Data-Driven and Last Click. First-click, linear, time-decay and position-based were retired in 2023, and any conversion actions using them were auto-migrated to data-driven. Data-driven is now available to every account with no minimum-conversion requirement.
1What an attribution model does

It decides which click gets the credit

Customers often click more than one of your ads before converting. An attribution model decides how to split the credit for that conversion across those clicks — which directly shapes how each campaign looks in your reports, and what Smart Bidding learns to chase.

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Which attribution model fits?

Only two models exist now. Pick your typical purchase path and we’ll suggest one.

2The two models that remain

Data-Driven vs Last Click

ModelHow it creditsTrade-off
Data-Driven (DDA)AI spreads credit across touchpoints based on what actually drove conversions in your accountMost accurate and the default; the formula is a bit of a black box
Last Click100% to the final ad click before convertingSimple and predictable; ignores everything that came before

Last Click tends to over-reward closing branded searches — the click a buyer was going to make anyway — while starving the awareness and assist campaigns that actually started the journey. That’s the core reason Google made data-driven the default.

3Choosing & comparing

Use the Model Comparison report

For almost everyone, Data-Driven Attribution is the right call — it’s the default, it credits the whole path, and it feeds Smart Bidding better signals. Last Click is only really defensible when the journey is genuinely short and direct, or when you need consistency with historical last-click data.

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Don’t guess — compareGo to Goals → Measurement → Attribution → Model comparison to see how credit (and your CPA/ROAS) shifts between the two models on your real data before you commit.
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Model vs window are separateThe attribution model (who gets credit) is different from the attribution window (how far back Google looks — 30 days by default, up to 90). Set both deliberately per conversion action.
Key takeaways
  1. An attribution model splits conversion credit across the clicks on the path.
  2. Only two remain: Data-Driven (default, recommended) and Last Click.
  3. Last Click over-credits closing branded searches and ignores earlier touchpoints.
  4. Data-Driven credits the whole path and feeds Smart Bidding better signals.
  5. Compare the two in the Model Comparison report before you switch.
?Frequently asked

Attribution model FAQs

What attribution models does Google Ads have in 2026?
Just two: Data-Driven Attribution, which is the default, and Last Click. The first-click, linear, time-decay and position-based models were retired in 2023.
What is data-driven attribution?
A model that uses Google’s AI to spread conversion credit across the touchpoints that actually drove conversions in your account, rather than following a fixed rule.
What is last-click attribution?
A model that gives 100% of the conversion credit to the final ad click before the conversion, ignoring any earlier interactions on the path.
Which attribution model should I use?
For most advertisers, data-driven attribution, because it credits the whole path and feeds Smart Bidding better. Last click suits only very short, direct purchase journeys or historical consistency needs.
Does data-driven attribution need a minimum number of conversions?
No longer. Data-driven attribution is now available to all accounts with no minimum-conversion requirement, which is why it became the sensible default.
What is the difference between an attribution model and an attribution window?
The model decides who gets credit for a conversion, while the window decides how far back Google looks for ad interactions, with a 30-day click-through default that can extend to 90 days.
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Vikas Disale
Author · Digital Marketing

Vikas Disale is a digital marketer with around a decade of hands-on experience running and teaching paid search. He builds practical, example-led Google Ads training for business owners and marketers. More about Vikas →

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