Google Ads Smart Bidding has quietly shifted from an option to the default engine under Performance Max, AI Max for Search, Demand Gen and most App campaigns. The four strategies? Target CPA, Target ROAS, Maximize conversions and Maximize conversion value. They all do one thing differently from old manual bidding: they set a separate bid for every single auction.
What auction-time bidding actually means
Instead of one keyword bid that stays the same all day, Smart Bidding reads more than 20 signals at auction time: device, location, time, audience lists, the actual query and more. It combines those signals into a predicted conversion likelihood, and for value strategies an expected conversion value, then bids against the objective you chose.
- Target CPA tries to keep cost per acquisition around your stated target.
- Target ROAS tries to keep conversion value divided by cost at your target percentage.
- Maximize conversions and Maximize conversion value chase volume or revenue within a fixed daily budget.
The arithmetic can be simple even when the model is not. A click with a 4% predicted conversion rate under a 50 euro Target CPA is worth about 2 euros. If the same keyword sits in a context where that prediction falls to 1%, it is worth 50 cents. That is the core promise: context changes value, and the machine re-prices every time.
The August 17 change marketers are debating
From August 17, 2026, budget-constrained campaigns using Target CPA or Target ROAS steer toward the stated target instead of beating it. In practice, a campaign achieving a 30 euro CPA against a 60 euro target can drift up toward 60. Ginny Marvin, Google’s Ads Liaison, denied this was a broader Smart Bidding overhaul, but one advertiser reported the change cut Shopping sales at a 300% target ROAS.
The argument is really about leverage. Google runs the auction, sells the inventory, operates the bidder and reports the conversions. Advertisers can see averages and a short list of top signals, not the bid placed in each auction or the weight given to any signal. That opacity makes it hard to separate a model error from a market shift.
The inputs you still control
Smart Bidding has not removed strategy work; it has moved it upstream. Conversion actions decide what counts as success, and only primary actions steer bids. Conversion values tell value strategies what each outcome is worth. Enhanced conversions widen what the model can observe by matching hashed first-party data to ad interactions.
Portfolio bid strategies pool data and targets across campaigns and allow maximum and minimum bid limits. Seasonality adjustments tell the model to expect short-term shifts, and data exclusions remove broken tracking periods. Google says models now train on account-level conversion data, so a new campaign does not start from zero, but you should still judge Target CPA after at least 30 conversions and Target ROAS after 50.
Smart Bidding Exploration, launched in May 2025 and now expanding to Performance Max and Shopping, deliberately bids on queries without conversion history in exchange for a tolerated ROAS dip. Google reports an average 18% rise in unique converting search query categories for campaigns using it.
Recent moves underline the direction. In June 2026 Google restored Target CPA and Target ROAS as standalone labels and added promotion mode for short-term ROAS tolerance changes. In September it introduced Qualified Future Conversions, counting conversions up to 180 days after a click. Microsoft Advertising drops maximum CPC from new campaigns on October 1, 2026, so the manual escape hatch is closing elsewhere too.
Source: PPC Land
