Google sets no minimum to turn on most Smart Bidding strategies, and says Target CPA works with no conversion history. Target ROAS is the exception: Search and Shopping campaigns need at least 15 conversions in the past 30 days. To judge results, Google recommends periods with at least 30 conversions (50 for Target ROAS).
There is no official "30 conversions a month" rule for switching on Smart Bidding. Google's help center says you can turn on Smart Bidding without prior data, and that it can learn from all the campaigns in your account, so even a new campaign without its own conversions can benefit.
The numbers people quote usually mix up two things: what you need to turn a strategy on, and what you need to judge whether it works.
What are the minimums for each strategy?
Google lists no conversion minimum for Target CPA or Maximize conversions, and says advertisers can start using Target CPA with no conversion history. You only need conversion tracking set up.
Target ROAS is the strategy with hard requirements, and they depend on the campaign type (as of November 2026):
| Campaign type | Target ROAS needs |
|---|---|
| Search and Shopping | At least 15 conversions in the past 30 days |
| Display | At least 15 conversions with valid values in the past 30 days, across all campaigns (new Display campaigns no longer need a history) |
| Demand Gen | At least 50 conversions in the past 35 days in the campaign, with 10 in the past 7 days, or 100 in 35 days across all Demand Gen campaigns |
| Video action | At least 30 conversions in the past 30 days |
| App | At least 10 conversions a day, or 300 in 30 days |
For Maximize conversion value in Search and Shopping, Google gives no fixed number. If you only just started reporting conversion values, it recommends waiting 1-2 conversion cycles before you switch.
How many conversions do you need to judge the results?
This is where the bigger numbers come from. Google recommends measuring Smart Bidding performance over periods that have at least 30 conversions, such as a month or longer, and 50 conversions for Target ROAS.
Timing matters too. After a new strategy or a big structural change, the "Learning" status shows for up to 7 days. Google says performance usually settles on the new goal within 1 to 2 conversion cycles, and suggests evaluating over 2 conversion cycles or 2 weeks after that, whichever is longer.
If your conversion volume is low, read my guide to conversion cycles and learning periods before you judge a strategy too early.
What if your campaigns get very few conversions?
Google's own advice for low volume is to give the system more data, not to avoid Smart Bidding:
- Combine campaigns and ad groups where you can, so conversions pool together. Google notes that performance generally improves with fewer, larger campaigns.
- Bid toward one consistent primary conversion goal.
- Add relevant keywords to low-volume campaigns to widen reach.
In my experience, the real problem with a handful of conversions a month is noisy reporting, not the algorithm. One good or bad week swings your CPA a lot. I would rather merge small campaigns, or bid on a micro conversion that happens more often, than spread a small budget thin. More on this in my post on low conversions with Smart Bidding.
Sources
- Google Ads Help: About Smart Bidding - https://support.google.com/google-ads/answer/7065882?hl=en
- Google Ads Help: About Target ROAS bidding - https://support.google.com/google-ads/answer/6268637?hl=en
- Google Ads Help: About Target CPA bidding - https://support.google.com/google-ads/answer/6268632?hl=en
- Google Ads Help: About Maximize conversion value bidding - https://support.google.com/google-ads/answer/7684216?hl=en
- Google Ads Help: About Smart Bidding learning - https://support.google.com/google-ads/answer/13020501?hl=en