There is no right number for the target box
One week into Google's August 2026 rollout, I saw more movement in cost per acquisition than usual across several accounts. That observation is a reason to investigate, not proof that one platform change caused every movement. This article separates Google's published change from my operating argument.
What Google actually changed
On 17 August 2026, Google began a gradual rollout for affected campaigns that are limited by budget and use target-based bidding. Google says those campaigns will perform more consistently toward their bid target. Its worked example is a campaign with a target CPA of $10 that had been delivering around $5 because the budget ran out first; after the change, Google says delivery can move closer to $10.
Target CPA was already an average rather than a per-conversion ceiling. The new point is narrower: affected campaigns that previously overperformed the target while limited by budget may now deliver more closely to the target they state. Google does not say every campaign will land exactly on the number, that CPC must rise, or that every result below target will be pushed up.
Google offers several responses. These include reviewing budgets and targets, using its Bid Target Adjustment Tool, and switching to Maximise conversions or Maximise conversion value without a target to seek the highest volume or value within a set budget.
Why the same budget can buy less
The arithmetic is simple even though auction causality is not. CPA equals spend divided by conversions. If spend stays fixed and actual CPA rises from $5 toward $10, conversion volume falls. That does not tell us which bids changed or why an individual auction was won, but it does describe the business outcome.
This is why an old target with lots of apparent headroom now deserves review. A $10 target attached to a campaign actually delivering at $5 no longer looks merely decorative when Google says affected delivery will become more consistent with the stated target.
Why changing the number is not automatic
The Bid Target Adjustment Tool can suggest a target informed by recent actual performance. That is a documented option, not a guarantee that the recent average is the correct commercial constraint.
A trailing CPA mixes seasonality, auction conditions, conversion lag, campaign changes and the quality of the conversion goal. Copying it into the target field preserves the number without answering whether the business wants maximum volume, maximum value or a hard efficiency floor.
My conclusion is therefore about one specific objective. If a campaign is genuinely limited by a fixed budget and the advertiser wants the highest possible conversion volume or value from that budget, there may be no independently meaningful CPA or ROAS number to type. The target can become a second constraint on top of the spend constraint.
That is not the same as saying targets are always bad. If the advertiser will buy any available volume only above a particular return, the efficiency target is the business objective. If cashflow, margin or a contract makes CPA a hard limit, retaining a target can be rational even when it reduces volume.
An average target does not describe the full spread of campaign and daily outcomes.
An operating argument, not a Google fact
Here is the clean conceptual argument.
Call the fixed budget B. Maximise conversions is asked to seek the most selected conversions within B. Adding a target CPA introduces an efficiency condition. In a simplified optimisation problem with the same objective, data and ranking, an extra constraint cannot improve the theoretical maximum; it can be inactive or remove feasible auctions.
Real Smart Bidding is not that simplified proof. Strategies can learn and rank differently, values can be wrong, conversion data can be sparse, and removing a target changes system behaviour. The optimisation argument explains why a target-free strategy is coherent for a maximum-output objective. It does not prove that a live Google campaign will improve after the switch.
Google's own documentation supports the option, not the outcome. It lists Maximise conversions or Maximise conversion value without a target for advertisers who want the highest volume or value from their set budget.
When spend is the business limit, budget can be the explicit boundary. The result still depends on the goals and data inside it.
The conversion signal matters first
A bidding-strategy debate is secondary if the account counts the wrong outcome. Target CPA optimises the conversions included in its goal. Maximise conversions does the same without an average CPA target. Neither strategy knows that a duration-only call was an existing customer, or that one form became a high-margin job, unless the advertiser supplies a better goal or value.
For that reason, I would not remove a target and declare the job done. First check which actions are primary, whether phone and form outcomes reach the CRM, whether eligible offline imports work, and whether conversion values reflect expected contribution rather than arbitrary platform defaults.
Maximise conversion value is useful only when those values deserve to steer. Bad values at scale are not better than an arbitrary CPA target.
What the account examples do and do not prove
One account I reviewed had Demand Gen, Search and Performance Max campaigns reporting materially different CPAs over the same period. A Google representative suggested a target based on the trailing average. I asked which number should apply when the best campaign was already well below that average.
That call sharpened my view that a trailing account average is not automatically a defensible campaign target. It remains an anecdote from an account review, not documentation of Google's internal mechanics, a statement of Google policy, or proof that the representative's answer applies elsewhere.
The same caution applies to movements after 17 August. A before-and-after change in CPA can be evidence worth monitoring. Without a controlled test and enough time for conversion lag, it is not clean causal proof.
Honest limits of the argument
Removing a target can trigger a learning or settling period. Google recommends allowing one or two conversion cycles after changes before judging performance. Repeated changes inside that window make the result harder to interpret.
Campaigns marked Limited by budget can move in and out of that status. On days when budget is not binding, a target may be doing real work. Shared budgets and portfolio strategies also need review at their shared scope.
A target can be valuable insurance against an efficiency tail the business cannot tolerate. Insurance can reduce expected volume and still be worth buying.
And the reported objective may itself be wrong. Maximum platform conversions is not maximum profit if the conversion goal includes weak leads. Maximum platform value is not maximum contribution if the values are revenue guesses.
What to do
Pull the campaigns covered by Google's rollout that are marked Limited by budget and use a target-based strategy. Then answer these in order:
- Are the primary conversion actions real business outcomes, and are their values defensible?
- Is the budget consistently binding, or only occasionally?
- Is the objective maximum volume or value from fixed spend, or is CPA or ROAS a hard business constraint?
- What conversion-cycle length and lag should govern the review window?
If the objective is maximum volume or value from a genuinely fixed budget, test Maximise conversions or Maximise conversion value without a target. Record the change, avoid simultaneous structural edits, and judge it after at least one or two conversion cycles.
If efficiency is the true constraint, keep or adjust the target from contribution, cashflow and risk tolerance. Do not reduce budget and pretend that this creates a CPA ceiling; budget limits spend, not the cost of an individual conversion.
The strong claim on this page is therefore a decision rule, not a universal platform law: for the fixed-budget advertiser whose real objective is maximum output, there may be no right number for the target box because the target is not the objective.
Sources checked
- Google Ads: August 2026 target rollout
- Google Ads: options for affected campaigns
- Google Ads: about target CPA bidding
- Google Ads: Smart Bidding learning and conversion cycles
17 August: Google converted a setting into a job · Budget is the limiter · Targets from unit economics