Smart Bidding is the group of Google Ads bid strategies that use Google’s machine learning to set a separate bid for every auction, aiming to win you more conversions or more conversion value. Instead of choosing a cost per click yourself, you tell Google what outcome you want and, optionally, what you are willing to pay for it.
How Smart Bidding works
There are four main Smart Bidding strategies:
- Maximise conversions: spend the budget to get as many conversions as possible.
- Target CPA: get as many conversions as possible at or near an average cost per acquisition you set.
- Maximise conversion value: spend the budget to get the most total value, such as revenue.
- Target ROAS: get as much value as possible at a return on ad spend you set.
At every auction, Google looks at signals you could never weigh by hand: the device, location, time of day, the exact search, the browser, whether the person is on one of your remarketing lists, and many more. It predicts how likely this particular search is to lead to a conversion, and how valuable that conversion would be, and bids accordingly. A search for “emergency electrician Bristol” from a phone at 10pm might get a much higher bid than a desktop search for “how to rewire a plug” at noon.
Other automated strategies, such as maximise clicks and target impression share, also set bids for you but aim at clicks or visibility, not conversions, so they are not counted as Smart Bidding. Enhanced CPC, which used to sit in this group, has been withdrawn from most campaign types.
Why it matters
Smart Bidding is now the default way to run most Google Ads campaigns, and Performance Max depends on it entirely. When it is fed good data, it usually beats manual bidding because it adjusts to every auction rather than to averages.
The weak point is the data. Smart Bidding optimises for whatever you tell it is a conversion. If your tracking counts newsletter sign-ups, page scrolls and real enquiries as equal, the system will chase the cheap ones. In the UK there is an extra factor: consent. Under PECR, advertising cookies, including those Google Ads uses to record conversions, need consent, so visitors who decline are not observed directly. Google’s consent mode fills part of the gap with modelled data, but a badly set up consent banner can quietly starve Smart Bidding of the signals it needs.
Common mistakes
- Switching on Smart Bidding before conversion tracking is accurate, or with only a handful of conversions a month.
- Counting soft actions, such as clicks on a phone number or visits to a contact page, as primary conversions alongside real leads.
- Setting a target CPA far below what the account currently achieves, which tends to choke volume.
- Changing targets and budgets every few days, so the strategy never settles out of its learning period.
- Forgetting to exclude days when tracking broke, so the system learns from false data. Data exclusions exist for this.
- Using revenue as the value for value-based bidding when margins vary widely between products.
How to act on it
Fix the measurement first. Check that each primary conversion action is something that matters to the business, that it fires once per real conversion, and that enhanced conversions and consent mode are set up properly. If you are a lead-generation business, consider feeding back which leads became customers, so Google learns from quality rather than form fills.
Start with maximise conversions or maximise conversion value to gather data, then add a target once you know what the account can achieve. Set targets close to current performance and move them in small steps, giving each change a couple of weeks. Bid strategy choice and conversion setup are at the centre of how I run PPC management for UK businesses.