Facebook’s official recommendations on how to use Campaign Budget Optimisation

27. 3. 2020

Since the launch of Campaign Budget Optimisation, aka CBO, many advertisers have benefited by the easy way to distribute the budget to the best performing campaigns based on real-time data. We sat down with Claire-Louise Fagan, a Marketing Science Expert at Facebook, and asked her to share her knowledge on how, when and tips on using CBO the right way.

Q: What is the recommended CBO structure for acquisition and remarketing campaigns in terms of the number of Ad Sets and Ads, targeting audience size, etc.?

A: In terms of ad spend, it should be around 70% on prospecting, 20-30% on retargeting and 0-10% on loyalty programs campaigns.

The recommended structure is having ideally 2-5 ad sets and within each ad set roughly 5 ads. Lastly, for the targeting audience size, we recommend the audience to be as broad as possible. When it makes sense, group together interest & behaviour targets.

Q: Is there a “formula” to help calculate how much budget to allocate to a CBO campaign also, what should one take into account when deciding on the budget? 

A: When thinking about the campaign budget, we need to consider what budget will get us at least 50 conversions per week per ad set. To calculate an efficient amount of an ideal weekly budget, consider the following formula: Average CPA X 50 X Number of ad sets. If you are calculating a daily budget, you can divide this formula by 7.  The budget should be greater than that. 

Ideally, you want to get 50 conversions per ad set per week so they are performing optimally and thereafter the algorithm can decide in which ad sets the budget will be spent for the most cost-effective conversion. If you have a budget that is not spending and are using a bid cap, it means that your bid cap is too low and you need to increase it so it’s at least 20-30% higher than an average CPA.  

Q: How long does it take to optimize a CBO campaign and what are the factors that go into that?

A: Before the system can decide where to spend your budget effectively, ideally it wants to understand which ad sets are performing optimally. To ensure this, we need to make sure that each ad set generates at least 50 conversions per week. 

Q: Does replacing and/or adding new creatives reset the learning phase per ad set per time? Does this, in turn, affect the performance of the whole CBO campaign?

A: Adding new creative means that the system will try to learn how effectively this creative is performing so this ad set will go into the learning phase. 

If this newly added creative is allowing the ad set to get results for lower CPA than the other ad sets in the campaign, then the budget will shift to this particular ad set. If it’s however more expensive, then it will continue to spend the budget on the better performing ad sets within your campaign. 

Q: Can I run more than one campaign with CBO for different objectives without having to worry about audience overlap?

A: It depends on how similar those objectives are. If the advertiser is optimizing for opposite funnel signals, for example, one campaign is optimizing for “ViewContent” and another one for “Purchase”, the audience within the selected targeting would have different behaviour and wouldn’t be causing significant overlap. If, however, there are 2 campaigns optimizing for very similar lower funnel events (e.g. “Add to cart”, “Purchase”) there might be a higher chance of overlap. 

To avoid this issue, we suggest using broad targeting so the system has enough opportunities for the particular optimization event.  If you are using small audiences for similar lower funnel events, we recommend using exclusions. 

Q: Is it possible to run an evergreen campaign with CBO? If so, what would the structure look like?

Evergreen campaigns can be run like any other campaigns following CBO best practices. CBO is a dynamic process where the algorithm is always accessing all ad sets for the lowest predicted CPA.

Therefore, even if it appears that the budget is not spending in certain ad sets, do not pause these as the algorithm is currently spending in the most cost-effective ad sets. But if the predicted CPA increases within the ad sets where it’s currently spending budget, it will shift the budget to the other ad sets which are now more cost-effective. However, it cannot shift the budget if the other ad sets have been paused.  

Q: How successful is CBO with Dynamic Ads campaigns? (Can we have data?)

CBO and Dynamic Ads allow the Facebook algorithm to find where the most opportunity lies for the specific advertiser’s campaign objective (in this case a catalog sale). It will then deliver the most spend to the ad set that provides the most effective cost per result. 

Below there are two case studies where Campaign Budget Optimisation can be used in combination with Dynamic Ads, to boost performance.



Q: How does CBO work when I use different scheduled time periods for different Ad sets?

A: It is possible to add additional ad sets to campaign running with CBO, however, 2 considerations should be taken into account:

  1.  When adding a new ad set, the algorithm will try to get 50 conversions to get out of the learning phase. 
  2.  We recommend not doing scheduling or pausing of ad sets. If there is an ad set that has been paused or not been added and would provide cheaper opportunities, the system would not take advantage of this ad set. 

Q: Is CBO going to be obligatory for all campaigns? When?

A: Ad Accounts started migrating to using CBO effective since February 27th 2020.  We are conducting a phased rollout in order to provide additional time for advertisers to incorporate CBO into their campaigns. We expect our platform to become CBO-only over time, and encourage advertisers to continue testing and integrating the product into their buying strategy. 


In Business Factory, I work as a Facebook Marketing specialist helping both Czech and international clients to enhance their Facebook advertising efforts. For you, I wear my data-glasses and creative ideas-hat and share with you the tips, suggestions and tutorials that will help you step up your Facebook marketing game.


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