Google Ads Attribution Models: Which One to Use

When a customer clicks several ads before buying, someone has to decide which click gets the credit. Google Ads attribution models make that decision, and the choice changes the conversion numbers your bidding uses. This guide explains the models available now, how to switch and how to compare them before you commit.

What Attribution Models Do

An attribution model is a rule for splitting credit across the ad interactions that led to a conversion. The rule changes which keywords and campaigns look like winners, and it feeds the numbers that Smart Bidding learns from.

The Models Available Today

Google’s help page on attribution models lists two supported models:

Data-driven. Splits credit across ad interactions based on your account’s past data for that conversion action. Google says it is the default for most conversion actions.
Last click. Gives all the credit to the last ad that was clicked and its keyword.

Older rule-based models such as first click, linear, time decay and position-based are no longer supported. Google moved conversion actions that used them to data-driven attribution, and you can switch to last click if you prefer.

Which Model Should You Use

For most accounts, data-driven is the sensible default. It looks at how your customers behave, so it can reward earlier clicks that start the journey as well as the final one. That matters if you run broader campaigns that introduce people to your business.

Last click is simpler and easier to explain. It can suit accounts with short buying journeys, where one click usually leads to the sale. It tends to favour bottom-funnel terms, so brand and exact match keywords can look stronger than they are.

How to Change the Model

Go to Goals, then Summary.
Select the name of the conversion action.
Choose Edit settings, then Attribution model, and pick a model.
Save and select Done.

If you use cross-account conversion tracking, Google says to set the model in the manager account. A model change applies going forward to the conversions columns, and to bid strategies that use them, such as Target CPA. It does not rewrite the past.

Compare Before You Switch

The model comparison report under Goals and Attribution lets you view two models side by side. Use it to see which campaigns gain or lose credit. If a campaign loses a lot under the new model, check whether it is truly weak or just early in the journey.

The same lesson applies to your tracking setup. Credit can only go to conversions that are recorded, so fix gaps first. Our guide to tracking conversions in Google Ads covers the basics, and our guide to offline conversion import helps when sales close away from your website.

How Attribution Affects Bidding

Smart Bidding optimises toward the conversions it sees. When credit moves between campaigns, bids move with it, and performance can shift for a while. Make model changes one at a time and avoid other large edits at the same moment. Our guide to Smart Bidding explains how the strategies learn.

How Google Ads Attribution Models Move Credit

A hypothetical journey shows the effect. A customer clicks a broad keyword ad, returns a few days later through a brand search ad and then buys. Under last click, the brand ad gets all the credit, so the broad keyword looks useless. Under data-driven attribution, the credit is shared in a way that reflects how interactions like these usually contribute in your account.

That difference changes decisions. If you judge the broad keyword by last-click results, you may cut it and later see brand searches fall. The model you choose should match how you want to evaluate each stage of the journey.

A Checklist Before Changing the Model

Note your current conversions, cost per conversion and bidding targets.
Run the model comparison report for the conversion action.
Check whether any bid strategies depend on that conversion action.
Make the change in one place, and write down the date.
Review results after the bidding has had time to adjust, and compare against your notes.

Common Ways to Misread Attribution Data

Comparing periods under different models. A model change alone can move numbers, so mark the date of the change in your notes.
Judging campaigns on credit alone. A campaign that starts journeys may show low credit under last click yet drive real sales.
Ignoring conversion lag. Recent days can look weak because some conversions are still to come.

Treat attribution as one input. Combine it with your sales data and the way customers say they found you.

Document the Decision

Record which model each conversion action uses and why you chose it. Attribution settings are easy to forget, and a new team member comparing numbers across accounts can draw the wrong conclusions if one account uses a different model. A short line in your account notes saves hours of confusion later and keeps reporting consistent from month to month.

Frequently Asked Questions

Will changing the model change my past data?

No. Google says a change affects the conversions columns going forward, though the current model columns can show how past data would look under the new model.

Is last click wrong?

It is a valid choice, but it ignores earlier clicks. Compare it with data-driven in the comparison report before you decide.

Final Thoughts

Pick among Google Ads attribution models by looking at how your customers buy, then test the change with the comparison report. Keep tracking accurate, change one thing at a time and judge the result on conversions that matter to the business.

Want expert help with your account? See our Google Ads management service.