Smart Bidding Explained: Target CPA vs Target ROAS vs Maximize Conversions

Target CPA, Target ROAS and Maximize Conversions all promise the same thing: let Google’s AI set your bids. They aim for different goals, though. Pick the wrong one and you either waste spend or cap growth you could have had.

This post explains what each strategy does, using Google’s own help pages, and how to choose between them. We checked every Google fact below on 4 October 2026. Where the advice is our own judgment, we say so.

Quick summary, if you’re short on time:

• Maximize Conversions tries to get the most conversions while spending your full budget. It has no cost target.
• Target CPA aims for an average cost per conversion that you set. Google says you can start using it with no conversion history.
• Target ROAS aims for a return on ad spend that you set. For Search and Shopping campaigns, Google requires at least 15 conversions in the past 30 days, and you must set values on your conversions first.
• All three need conversion tracking. Without it, Smart Bidding has nothing to learn from.
• Google renamed “Maximize conversions with a Target CPA” to “Target CPA” and “Maximize conversion value with a Target ROAS” to “Target ROAS” from June 2026. The behavior did not change.

Jump to a section:

• The three strategies on one page
• Maximize Conversions: growth with no cost target
• Target CPA: a cost per lead you set
• Target ROAS: bidding on value, not just volume
• What about Maximize Clicks?
• Which one fits your business
• After you choose: how to judge it
• A prompt to check your numbers
• Questions about Smart Bidding

The three strategies on one page

Google’s guide to choosing a bid strategy starts from your advertising goal, such as conversions, clicks, impressions or views. It names Target CPA, Target ROAS and Maximize Conversions among its Smart Bidding strategies. For a business that wants enquiries, these are the three to compare.

Maximize Conversions: growth with no cost target

Google says Maximize conversions uses its AI to set bids to help get the most conversions for your campaign while spending your budget. There is no cost target. It will try to fully spend your average daily budget, so Google warns that if you are currently spending much less than your budget, Maximize conversions could increase spend significantly.

Other points from Google’s page:

• You must set up conversion tracking to use it.
• Your existing bid adjustments are not used, with one exception: you can still set device bid adjustments to -100%.
• It is designed to spend the full daily budget, so campaigns on it are limited by budget by design. Google says not to use the “Lost IS (budget)” column with it, and to use the budget simulator and impression share metrics to judge the budget opportunity.
• If you have a specific cost goal, Google says to use Target CPA instead.

Target CPA: a cost per lead you set

Target CPA is an automated bid strategy that sets bids to get as many conversions as possible, while you set the average cost per conversion you want. Google uses your target and the likelihood of each ad to convert to set the bid.

A few details matter in practice:

• No history needed. Google says advertisers can start using Target CPA with no conversion history, and that it is effective for campaigns of all sizes.
• It is an average. Some conversions will cost more than your target and some less. Your actual cost also depends on things Google does not control, such as changes to your website or ads, or more competition.
• A target that is too low can backfire. Google says it may make you give up clicks that could have converted, which means fewer total conversions.
• Google suggests a starting number. If your campaign has conversion history, the recommended target is the average CPA from the last 30 days, adjusted for conversion delays.
• Do not set bid limits. Google says this is not recommended, because it can stop the strategy from optimizing your bids.
• Budget headroom. Google recommends being comfortable spending up to 2 times your average daily budget, while not going over the monthly charging limit. It evens out over time.

Target ROAS: bidding on value, not just volume

Target ROAS uses Google’s AI to predict the value of a conversion each time someone searches, then sets bids to get the return you asked for. A search likely to bring a high-value sale gets a higher bid, and one that is unlikely to convert well gets a lower one.

It only makes sense when conversions carry different real values, like an ecommerce store where order sizes vary. Google’s requirements and tips:

• You must set values for the conversions you track before you can use it.
• For Search and Shopping campaigns, Google lists at least 15 conversions in the past 30 days at the conversion tracking level.
• Requirements differ by campaign types. Google lists 15 conversions in 30 days for Display too, at least 10 a day (or 300 in 30 days) for App campaigns, and at least 30 in 30 days for Video action campaigns.
• If you recently started reporting conversion value, Google recommends waiting 1 to 2 conversion cycles before adopting it.
• A target that is too high may limit the traffic your ads get.
• To get more volume, Google suggests gradually reducing the target. After a change, give it 1 to 2 conversion cycles.

What about Maximize Clicks?

Google describes Maximize Clicks as the simplest way to bid for clicks: you set a daily budget and the system tries to get the most clicks within it. Google says it can be useful for new campaigns that lack enough conversion data for Target CPA or Target ROAS, or when your main goal is website traffic and not direct conversions.

It is not a good choice if you need to hold a specific cost per conversion, because it does not optimize for conversions. For a service business that wants calls and forms, we treat it as a short starting step at most, and move to a conversion-based strategy as soon as tracking is working. That part is our judgment, not Google’s.

Which one fits your business

• You want enquiries and have no cost ceiling yet: Maximize Conversions, with a budget you are comfortable spending in full.
• You know what a lead is worth and want to hold the cost: Target CPA. Google says you can begin without history, but a target far from your real cost per lead will cause trouble, so check your recent average first.
• Conversions have different values and you track them: Target ROAS, once you clear the 15-conversion requirement and have set real values.
• Tracking is not working yet: fix that first. Our guide to setting up conversion tracking covers the setup, and none of these strategies can learn without it.

For a small local service business with a simple goal of calls and forms, we often start with Maximize Conversions or Target CPA. Which one depends on whether you have a cost per lead you must stay under. That is our usual approach, not a Google rule.

After you choose: how to judge it

• Give it time. Google says changing a bid strategy or its settings puts it into a “Learning” status while it adjusts. Making many changes keeps resetting that.
• Check where the click lands. The strategy can only count what your tracking records, so make sure each landing page records the conversion you care about.
• Judge it on enough data. For Target CPA, Google recommends measuring performance over the last 30 days with at least 30 conversions. With fewer, the numbers move around a lot.
• Compare the right numbers. Your average target CPA or ROAS can differ from the target you set, because of device adjustments and past changes. Compare your achieved result with the average target column.
• Know about the August 2026 change. From 17 August 2026, Google updated how Target CPA and Target ROAS behave on campaigns limited by budget, which can cause temporary fluctuations. Our post on Google Ads bid suppression explains it.

A prompt to check your numbers

An AI tool can help you check your own account against Google’s requirements. Paste in real figures from the last 30 days, and confirm the result in Google Ads before you switch anything.

Act as a careful Google Ads analyst. I will give you my last 30 days of campaign numbers. Check them against Google’s rules for Smart Bidding and tell me which strategy fits.

My numbers (last 30 days):
– Campaign type and goal: [for example, Search, phone calls and forms]
– Spend: [amount]
– Clicks: [number]
– Conversions: [number], and what counts as a conversion: [calls, form submissions, purchases]
– Do my conversions have different values: [yes with the values, or no]
– Average daily budget: [amount], and how much of it I usually spend: [percent]
– Current bid strategy: [name, and how long I have used it]

Please do the following:
1. Work out my cost per conversion, and show the sum.
2. Say whether I meet Google’s requirement of at least 15 conversions in 30 days for Target ROAS on Search, and whether I have enough conversions (30) to judge a strategy fairly.
3. Recommend one strategy, and explain why in plain words.
4. Tell me what could go wrong in the first two weeks after switching.

Rules:
– Use only my numbers. Do not invent benchmarks or promise a cost or return.
– If I am missing something, tell me what I need to find.
– Write in plain, simple English.

A recommendation based on wrong numbers sends you the wrong way, so check your conversion count and values in Google Ads first.

Questions about Smart Bidding

Where this matters

Smart Bidding strategies are not interchangeable settings. Each one optimizes for something different, so the right choice depends on your real conversion numbers and your goal, not on which sounds the most advanced. Fix tracking first, choose one strategy, and give it enough time and data before you judge it.

Want your bid strategy reviewed against your real account data? Our Google Ads management starts with exactly that check.