The essentials
- Definition: Smart Bidding covers the automated bidding strategies in Google Ads that adjust the bid at every ad auction according to the probability of a conversion.
- Six strategies: target CPA, target ROAS, maximise conversions, maximise conversion value, enhanced CPC and maximise clicks (the last of these outside conversions).
- Prerequisite: reliable conversions, 15 to 30 conversions a month per campaign, 4 to 6 weeks of learning with no major change.
- 2026 benchmarks: Smart Bidding is used on more than 80% of Google Ads spend; the typical gain against manual CPC is 10 to 30% more conversions on the same budget.
The aim of Smart Bidding (automated bidding) covers all the Google Ads bidding strategies that use machine learning to set the bid at every ad auction, according to how likely a click is to produce a conversion. Where an advertiser sets a single cost per click for a keyword, the algorithm varies the bid on dozens of signals: device, time, place, exact query, the user's history, browser, audience. How the platform works overall is described in Google Ads: definition and how it works.
The strategies available
| Strategy | What it optimises | When to use it |
|---|---|---|
| Target CPA | A set average cost per acquisition | Lead generation with a known cost per lead |
| target ROAS | A set average return on ad spend | E-commerce with reliable conversion values |
| Maximise conversions | Conversion volume within the budget | Getting started, or a budget to spend in full |
| Maximise conversion value | Revenue within the budget | Catalogues with uneven margins |
| Enhanced CPC (eCPC) | Adjusts the manual CPC up or down | Moving over from manual, low volume |
| Maximise clicks | Traffic, with no notion of conversion | Awareness, keyword testing; not Smart Bidding in the strict sense |
Target CPA and target ROAS are now options within the "maximise" strategies rather than separate strategies in the interface, but the logic is unchanged: give it a cost or profitability objective, or let the algorithm spend the budget as best it can. The notions of CPA and of ROAS govern the choice.
What the algorithm needs from you
- Reliable conversions: a clear definition of what counts as a conversion, with no duplicates, imported into Google Ads. An algorithm optimising a form counted twice learns a false reality.
- Volume: 15 conversions a month per campaign at minimum, 30 for a stable strategy. Below that, manual CPC or enhanced CPC remain preferable.
- Conversion values: for target ROAS, a real amount per sale; for leads, a value estimated by quality (a quote request is worth more than a download).
- Patience: 4 to 6 weeks of learning. Any change of budget, objective or structure above 20% restarts that phase.
- Consent: without Consent Mode properly deployed, a share of conversions isn't passed on and the algorithm underestimates real performance.
The 2026 benchmarks
More than 80% of Google Ads spend goes through an automated strategy in 2026, and manual CPC has disappeared from several campaign types (Performance Max, Demand Gen). The typical gain against well-run manual management sits between 10 and 30% more conversions on the same budget, more on high-volume accounts with pronounced seasonality. The trade-off is the loss of control: the advertiser no longer sets the bid per keyword, only the objective, the budget and the exclusions. Practical implementation is covered in automated Smart Bidding.
The mistakes that send an account off course
- A target CPA that is too low: the algorithm cuts delivery until it stops spending; the rule is to start from the observed CPA and bring it down 10 to 15% at a time.
- Changing the objective every week: every change restarts the learning and wipes out what was gained.
- Mixing conversions: counting contact page views and submitted quote requests in the same column makes it optimise for the cheapest.
- Ignoring brand: campaigns on the company name show a very low CPA that pulls the average down and hides acquisition; see the Google Ads KPIs.
- Over-segmenting: twenty campaigns at three conversions a month each starve the algorithm of data; grouping them together often performs better.
How GreenRed helps
Rather than juggling several tools, GreenRed's Google Ads module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
What is Smart Bidding?
All the automated bidding strategies in Google Ads that adjust the bid at each auction according to the probability of a conversion, using signals such as device, time, place, exact query and audience. The advertiser sets a cost or profitability objective, not a bid per keyword.
How many conversions do you need to use Smart Bidding?
Fifteen conversions a month per campaign at minimum, thirty for a stable strategy. Below that, enhanced CPC or manual CPC give better results, or you need to group campaigns together to concentrate the data.
Target CPA or target ROAS: which should you choose?
Target CPA for lead generation, when all conversions are worth roughly the same. Target ROAS for e-commerce or any business that passes on a real conversion value, so the algorithm favours the most profitable sales rather than the most numerous.
Why has my campaign stopped spending after switching to target CPA?
The target is probably too low against the real cost per acquisition: the algorithm gives up on auctions it judges too expensive. Raise the target to the CPA observed over the last thirty days, leave it six weeks, then bring it down in 10% steps.