Smart Bidding has become the backbone of modern Google Ads. Whether you're running Search, Performance Max, Demand Gen, or Shopping campaigns, automated bidding is now responsible for millions of auction-time decisions every day.
Because of
that, even relatively small changes in how Smart Bidding behaves can have a
noticeable impact on campaign performance, forecasting, and budget allocation.
A recent update
to Smart Bidding is a good example. While it doesn't introduce a new bidding
strategy or reporting feature, it does change how certain Target CPA (tCPA) and
Target ROAS (tROAS) campaigns behave when budgets become constrained.
For performance
marketers, this is worth understanding before making optimisation decisions.
Understanding
the Change
Historically,
many advertisers noticed an interesting behaviour in budget-constrained
campaigns.
Suppose a
campaign was running with:
- Daily Budget: €100
- Target CPA: €40
In many cases,
Smart Bidding would actually generate conversions well below the configured
target, perhaps at €24-€28 CPA, instead of spending aggressively until
it reached the full €40 target.
While this
often looked like excellent efficiency, it also created uncertainty.
Many
advertisers assumed the campaign simply couldn't spend more budget, while
others believed increasing the budget would automatically scale performance
without significantly increasing acquisition costs.
The latest
Smart Bidding behaviour aims to make optimisation align more closely with the
actual targets advertisers set.
Instead of
consistently trying to outperform the configured Target CPA or Target ROAS in
budget-limited situations, Smart Bidding is expected to optimise much closer to
the advertiser's defined objective.
In simple
terms, if you tell Google your acceptable CPA is €40, the system will
increasingly optimise around that target rather than consistently delivering
significantly lower CPAs simply because additional budget isn't available.
Why This
Matters
At first
glance, the change might appear insignificant.
In reality, it
affects several aspects of campaign management.
First, campaign
forecasting becomes more predictable.
If campaigns
optimise closer to the configured target, advertisers can estimate expected
acquisition costs with greater confidence when increasing budgets or planning
future investment.
Second, bid
targets become more meaningful.
Historically,
some advertisers intentionally set conservative targets knowing that Smart
Bidding often outperformed them. Over time, this created a gap between business
objectives and platform behaviour.
A Target CPA
should ideally represent the acquisition cost a business is willing to pay, not
simply act as a rough guideline that the system consistently exceeds.
Finally,
reporting becomes easier to interpret.
When actual
performance stays closer to defined objectives, optimisation decisions become
less dependent on hidden algorithmic behaviour and more closely aligned with
business goals.
Why Some
Advertisers Raised Concerns
Not everyone
welcomed the update.
Many
advertisers had become accustomed to campaigns delivering acquisition costs
comfortably below their configured targets.
For them, this
behaviour represented additional efficiency without requiring manual
intervention.
Naturally,
there were concerns that campaigns might now spend more aggressively, pushing
actual CPAs or ROAS closer to configured targets and potentially increasing
acquisition costs.
Those concerns
are understandable.
However, it's
also important to recognise the other side of the discussion.
If a business
defines a Target CPA of €40, then optimising consistently around €24
may not always provide the clearest picture of available demand, budget
limitations, or future scalability.
From a planning
perspective, predictable optimisation is often more valuable than unexpectedly
outperforming configured targets.
A Practical
Example
Imagine two
advertisers with identical campaigns.
Campaign
Settings
- Daily Budget: €100
- Target CPA: €40
Previous
Behaviour
The campaign
consistently delivered conversions around €24 CPA while remaining budget
constrained.
The advertiser
increased the budget expecting proportional growth while maintaining the same
acquisition cost.
Instead,
performance often changed unpredictably because the campaign had already been
operating significantly below its configured target.
Updated
Behaviour
The campaign is
more likely to optimise closer to the intended €40 CPA.
As budgets
increase, performance expectations become easier to forecast because campaign
behaviour is aligned with the objective originally defined by the advertiser.
While this may
appear less efficient on paper, it often provides a more realistic
understanding of what scaling actually costs.
My
Perspective
Personally, I'm
not convinced this is the right direction.
I understand
why Google wants Smart Bidding to optimise closer to the targets advertisers
define. Greater consistency makes forecasting easier, creates clearer
expectations, and reduces the gap between configured goals and actual campaign
performance.
From Google's
perspective, that makes sense.
However, from
the perspective of someone managing performance campaigns, I believe this
update also comes with trade-offs.
One of the
strengths of Smart Bidding has always been its ability to outperform
expectations when market conditions allowed it. If the system could
consistently acquire conversions at €24 against a Target CPA of €40,
that wasn't necessarily a flaw. It was evidence that the algorithm had
identified opportunities more efficiently than the target required.
Many
advertisers benefited from this hidden efficiency.
With the
updated behaviour, campaigns are expected to optimise much closer to the
configured target. While this makes campaign behaviour more predictable, it may
also reduce the upside that many advertisers had become accustomed to seeing.
In other words,
predictability may come at the expense of efficiency.
That doesn't
automatically make this a bad update.
For businesses
that prioritise financial planning, budgeting accuracy, and stable forecasting,
this change could be beneficial. Campaign performance should become easier to
explain internally, particularly when discussing expected acquisition costs
with finance or leadership teams.
On the other
hand, advertisers focused primarily on maximising efficiency may feel
differently.
If campaigns
naturally move closer to Target CPA or Target ROAS rather than consistently
outperforming those targets, some advertisers may end up paying more per
acquisition than they historically achieved, despite using the same bidding
strategy.
Ultimately, I
see both advantages and disadvantages.
What I like
- Campaign performance should become
more predictable.
- Budget planning and forecasting may
become easier.
- Bid targets will more accurately
reflect business objectives.
- Scaling decisions should become
more transparent.
What
concerns me
- Advertisers may lose some of the
"bonus efficiency" Smart Bidding previously delivered.
- Higher actual CPA or lower ROAS
could become more common for campaigns that historically outperformed
their targets.
- Some long-running accounts may need
to recalibrate performance expectations after the rollout.
- There is a possibility that
advertisers accustomed to lower acquisition costs may perceive a decline
in efficiency, even if campaign behaviour is technically more aligned with
configured objectives.
Overall, I
don't see this as a fundamentally bad update, but I also don't believe it's an
obvious improvement for every advertiser.
Like many
platform changes, the real impact will only become clear after advertisers have
had time to observe how their own campaigns perform in production. Until then,
I'd recommend monitoring performance closely before drawing conclusions or
making large-scale bidding adjustments.
What
Advertisers Should Do Next
Rather than
making immediate changes across every account, I would recommend reviewing
campaigns systematically.
✔
Identify campaigns currently marked as budget constrained.
✔
Compare configured Target CPA or Target ROAS with actual historical
performance.
✔
Review whether your bid targets genuinely reflect acceptable business outcomes.
✔
Monitor performance carefully after scaling budgets instead of assuming
historical acquisition costs will remain unchanged.
✔
Avoid making multiple structural changes simultaneously, making it easier to
isolate the impact of bidding behaviour.
Final
Thoughts
Automation
continues to improve every year, but successful performance marketing still
depends on defining the right business objectives.
This Smart
Bidding update reinforces an important principle.
Algorithms can
optimise towards the goals we provide, but they cannot replace strategic
decision making.
As automated
bidding becomes increasingly sophisticated, competitive advantage will come
less from understanding which bidding strategy to choose and more from knowing
how to define realistic targets, allocate budgets intelligently, and interpret
platform behaviour within the broader context of business growth.
For performance
marketers, that's where expertise continues to make the biggest difference.





