What you will find in this article
- What Maximize Conversions actually does and what Target CPA does, and why today they are not two separate strategies but two configurations of the same one
- The real difference between "spend the whole budget" and "respect a cost per action": the volume versus control axis
- The decision matrix per account: data maturity, CPA stability, launch phase or scaling phase
- What is officially documented by Google and what emerges only from field experience, kept separate
- Behaviours observed on real campaigns during the switch from one strategy to the other, flagged as inferences
- The practical workflow to choose, set up and transition without resetting the learning
You launch a new campaign with Maximize Conversions, it brings volume, the cost per conversion is acceptable. You switch it to Target CPA to "keep the cost under control" and from one day to the next volume collapses, impressions drop, and the actual CPA stays above the target you set. Same campaign, same Smart Bidding, opposite results. The reason is not chance: the two strategies optimize for different goals, and picking one at the wrong moment costs you volume or costs you efficiency.
The choice between Maximize Conversions vs Target CPA is not a question of "which one is better". It is a question of what you are asking the algorithm to do: maximize the number of conversions within the budget, or get conversions at an average cost you decide. These are two different questions, and each has its right moment.
This article clearly separates what is officially documented by Google from what emerges from direct experience managing accounts and observing campaign behaviour after the strategy switch.
What Maximize Conversions and Target CPA actually do
Before choosing you need to understand what each one optimizes for. They are often described as opposites, but today they are far closer than they seem.
This is the point that changes everything. On Search, Target CPA is no longer a standalone strategy separate from Maximize Conversions: it is the optional target field of Maximize Conversions. When you set a Target CPA inside Maximize Conversions, the strategy behaves exactly as the old standalone Target CPA did.
The practical question for those managing campaigns is therefore: given that today one is the "with target" version of the other, when does it pay to leave the target empty (pure volume) and when does it pay to set it (cost control)? Google's documented answer is that without a target the campaign is "limited by budget" by design and spends everything, while with a target it optimizes towards that cost goal.
The real difference: volume versus cost control
It all comes down to one axis: are you chasing volume or predictability of cost? The two strategies sit at the two extremes and have very different impacts on budget, learning and stability.
Decision matrix: which strategy for which scenario
This table summarizes the choice by scenario. Rows flagged as "Direct experience" come from observing real campaigns, not from official documentation, and are stated explicitly.
| Scenario | Recommended strategy | Priority | Main risk | Source |
|---|---|---|---|---|
| New campaign launch (zero conversion history) |
Maximize Conversions | Volume | Unpredictable CPA | Official Google Ads |
| Mature campaign, stable CPA | Target CPA | Cost control | Reduced volume | Official Google Ads |
| Budget limiting, you want to scale | Maximize Conversions | Full spend | Rising CPA | Official Google Ads |
| Tight margins, max CPA known | Target CPA | Efficiency | Campaign starved | Direct experience ⚠️ |
| Transition volume → efficiency | Max Conv + gradual target | Balanced | Learning reset | Direct experience ⚠️ |
| Seasonality or steep discounts | Maximize Conversions | Reactivity | Volatile CPA | Direct experience ⚠️ |
| Performance Max / Display | Max Conv (optional target) | Depends on goal | Target too tight | Google Ads + experience ⚠️ |
| High volume of low-quality leads | Target CPA | Quality over cost | Fewer total leads | Direct experience ⚠️ |
What actually weighs in the choice: learning, volume and budget
Maximize Conversions does not disapprove or penalize a campaign for having little history: on the contrary, it is the strategy designed to build it. Target CPA, instead, needs data to work. Setting it too early, on a campaign that does not yet have a reliable average CPA, is the fastest way to end up with declining impressions and unspent budget, not because the strategy is "worse", but because you are asking it to respect a constraint before it has the numbers to do so.
On the learning period the same reasoning applies to both: every significant change of strategy or budget restarts a phase of model adaptation. Switching strategy too often, or tightening the Target CPA in small, closely spaced steps, keeps the campaign in permanent learning, and it is the most underrated cause of unstable performance.
Inferences from direct campaign experience
Target CPA set too early: the most frequent case of a stalled campaign. Across the transitions I have managed, setting a Target CPA on a campaign with less than a meaningful conversion volume in the preceding weeks has almost always produced an immediate drop in impressions. The campaign does not "fail", it simply stops entering auctions where the predicted cost would exceed the target. Leaving Maximize Conversions without a target first to accumulate history, and only then introducing the target, gave far more stable results.
The Target CPA that actually works is rarely the "desired" one. I have repeatedly observed that setting the target to a value below the historical average CPA, hoping to "push" the algorithm to cost less, reduces volume without proportionally reducing cost. The starting point that worked best is the real average CPA of the last 30 days, then lowered in small steps spaced out over time, not all at once.
Maximize Conversions at scale: great for volume, watch the cost. On campaigns where I raised the budget while leaving Maximize Conversions without a target, volume grew but the cost per conversion rose as the algorithm bought more expensive auctions to spend everything. This is not a defect: it is the design. When the rising CPA crossed the sustainable threshold, switching to a Target CPA equal to the cost already reached stabilized the spend.
On the campaign goal, not on the strategy name. The useful choice is not "Maximize Conversions or Target CPA" in the abstract, but "right now, for this campaign, does volume matter more or does cost control?". The distinction between spending the budget and respecting a cost is real and documented; which of the two you need today depends on the account's phase, not on the strategy itself.
Practical workflow: choose and transition without damage
1. Start from the goal, not from the strategy. If the campaign is new or you want to scale and the budget is the constraint, use Maximize Conversions without a target. If the campaign is mature, converts predictably and the constraint is cost, go to Target CPA. If you are in between, start from Maximize Conversions and introduce the target later.
2. Check that you have the history before setting a Target CPA. Without a sufficient conversion volume and a stable average CPA in the preceding weeks, the Target CPA chokes the campaign. The practical rule:
if 30-day average CPA = unstable → stay on Maximize Conversions Build the history first, then set
the target.
3. Set the first Target CPA on the real cost, not on the desired one. Start from the actual average CPA of the last 30 days.
initial Target CPA ≈ real average CPA last 30 days Only after verifying stability, lower it in
small steps (10-15%) spaced at least one to two weeks apart, letting the learning settle between one change and the next.
4. Do not confuse "limited by budget" with a problem. On Maximize Conversions without a target the "limited by budget" label is intended: the strategy is designed to spend the full budget. Do not chase the "Lost IS (budget)" column, which is incompatible with this strategy. Focus on the real cost per conversion and on the campaign goal.
