How to Measure AI Max’s Share of Google Ads Conversions

Your Search campaign can gain conversions after AI Max is enabled while leaving you with a basic unanswered question: how much of the result came through AI Max rather than the keyword matches you already controlled? The visible search-query list cannot reliably answer it.

The useful measure is AI Max’s share of total campaign conversions. Google Ads places the numbers needed to calculate it in summary rows at the bottom of the Keywords table. Once you track that percentage by campaign, you can see where AI Max is changing the makeup of performance and reserve detailed query reviews for the campaigns that warrant them.

Measure AI Max’s contribution without calling it incremental lift

AI Max gives Google more freedom to match searches beyond the keyword structure you built. It can use your existing keywords, landing pages, assets, and other campaign signals to find additional searches. Google separates that activity into two matching categories:

• AI Max expanded matches: Searches found by expanding beyond your existing keywords.
• AI Max landing page matches: Searches found from landing pages and assets, including searches outside your normal keyword targeting.

Each category tells you something different. Expanded matches show how much Google is extending the logic of your keywords. Landing page matches show how much your pages and assets are functioning as matching inputs. Add the two categories when you want the overall AI Max contribution.

Total AI Max conversions = AI Max expanded match conversions + AI Max landing page match conversions

AI Max share of total = Total AI Max conversions / Total campaign conversions

If a campaign records 100 conversions and the two AI Max categories contribute 24 conversions between them, AI Max’s share is 24%. That is a contribution or attribution measure: 24% of the campaign’s recorded conversions were assigned to AI Max matching routes.

It is not proof that AI Max created 24 incremental conversions. The calculation does not tell you how many of those people would have converted through another match type if AI Max had been unavailable. That causal question requires a controlled comparison. Keep the label precise so a reporting percentage does not quietly become an unsupported claim about lift.

Keep the numerator and denominator aligned when you calculate the share:

• Use the same campaign and date range for every component.
• Use the same conversion column and conversion definition throughout the calculation.
• For an account-wide result, sum campaign conversion counts first and then divide. Do not average the campaign percentages, because a small campaign would otherwise receive the same weight as a large one.
• If total campaign conversions are zero, leave the percentage blank. A displayed 0% would imply observed performance when there was no denominator to evaluate.

Pull the complete totals from the Keywords report

The Search Terms report is the natural place to examine what people searched, but it is the wrong place to calculate AI Max’s complete conversion share. Some search activity is grouped under Other search terms; in some accounts, that hidden group has represented 40% or even 50% of total search activity. Adding the AI Max conversions attached only to visible queries can therefore leave a large part of the denominator unexplained.

Use the Keywords report for the complete contribution calculation:

1. Set the reporting date range you want to measure.
2. Select one Search campaign and open its Keywords tab.
3. Scroll to the bottom of the table, where Google displays its summary rows.
4. Record Total: Campaign, Total: AI Max expanded matches, and Total: AI Max landing page matches. Total: Your keywords is also useful when you want to see the non-AI-Max side of the campaign.
5. Add the two AI Max conversion totals and divide the result by total campaign conversions.
6. Save the counts as well as the percentage. You will need both to interpret a change correctly.

The summary rows roll up into the campaign total, so they provide a more complete base for the calculation than a list of visible search terms.

This does not make the Search Terms report unimportant. It changes its job. Use the Keywords summary rows to answer how much AI Max contributed. Use the Search Terms report to investigate what kinds of searches Google found after the percentage tells you which campaign deserves attention.

Turn the calculation into a weekly campaign scorecard

Opening campaigns individually is workable for a very small account. It breaks down when you manage 20, 50, or 100 campaigns. Google Ads exposes the necessary totals but does not make them easy to assemble into one campaign-level report.

Your scorecard needs six fields. Keep the two AI Max categories separate even though you also calculate a combined total; otherwise, you will see the contribution change without seeing which matching mechanism changed it.

In a spreadsheet where total conversions are in column B, expanded matches in C, and landing page matches in D, column E can add C and D. Column F can divide E by B when B is greater than zero and remain blank otherwise. Format F as a percentage.

For a larger account, this field list is also an automation specification. A Google Ads script can create a spreadsheet and populate the campaign-level report. Whether you automate it with a script or assemble it manually, the output should preserve the underlying counts rather than exporting only a percentage.

Refresh the scorecard weekly using a consistent reporting window. Add a prior-period share and calculate the change in percentage points. A move from one share to another should be described as a percentage-point change, not as a percentage increase, because those are different calculations.

Do not impose an arbitrary universal threshold and treat every campaign above it as a problem. A high share can reflect valuable expansion, and a low share can simply mean AI Max is playing a small role. Sort for the largest changes, then combine the percentage with conversion counts, CPA, and query relevance. The percentage is a triage signal, not a verdict.

Interpret the movement before editing the campaign

AI Max share is a ratio, so it can move even when AI Max conversion volume does not. Always inspect the numerator and denominator before deciding what happened:

• AI Max conversions and AI Max share both rise: AI Max is taking a larger role in the campaign. Review query quality and economics before treating the expansion as a win.
• AI Max share rises while AI Max conversions stay flat: Non-AI-Max conversions probably declined. The higher percentage does not demonstrate additional AI Max output.
• AI Max conversions rise while its share stays flat or falls: The campaign grew at least as quickly outside AI Max. The AI Max count improved without becoming a larger part of the mix.
• Landing page matches drive the change: Inspect the landing pages and assets involved. Their signals are increasingly responsible for searches outside the normal keyword structure.
• Expanded matches drive the change: Focus the query review on themes Google found by moving beyond your existing keywords.

Once a campaign is flagged, open its AI Max search terms and ask four concrete questions:

1. Are the visible searches relevant to the offer and the intent the campaign is meant to serve?
2. Are those searches converting at an acceptable CPA?
3. Is AI Max exposing useful query themes that your existing keyword structure does not cover?
4. Has the expansion become too aggressive for the campaign’s purpose?

Those checks turn the percentage into an optimization decision. Relevant searches at an acceptable CPA may justify keeping the expansion and deciding whether recurring themes deserve explicit coverage in your keyword plan. Irrelevant searches or unacceptable economics call for a more constrained response. First identify whether expanded matching or landing page matching is responsible, then make the narrowest available change to the corresponding inputs or controls.

Campaign edits can redirect spend, so do not make broad changes because of one surprising visible query. The visible query list is incomplete. Use the complete summary totals to establish materiality, make a scoped change, and check the next weekly snapshot to see whether the matching mix and performance moved in the intended direction.

A campaign with a low, stable AI Max share usually does not deserve the same review time as one whose share suddenly changes. That is the operational value of the metric: it narrows the account to the places where Google’s matching freedom is materially changing what the campaign does.

Key takeaways

• Calculate AI Max’s contribution from the summary rows at the bottom of the campaign’s Keywords report, not by adding only visible search terms.
• Add AI Max expanded match conversions and AI Max landing page match conversions, then divide by total campaign conversions.
• Treat the result as a share of attributed conversions, not as proof of incremental lift.
• Retain the two AI Max components, their combined count, and the campaign total in your report so changes remain explainable.
• Monitor the percentage weekly by campaign and investigate material changes rather than reviewing every AI Max query indiscriminately.
• Use Search Terms for qualitative diagnosis after the campaign-level metric tells you where to look.

In your next reporting cycle, capture one baseline across every AI Max campaign and repeat it with the same reporting window. Start your review with the campaign whose contribution mix changed materially and whose CPA or query relevance no longer supports that change. That gives you a defensible reason to act instead of reacting to whichever query happens to catch your eye.

References

• Search Engine Land – How much of your Google Ads conversions come from AI Max?