The Real Difference Between CBO and ABO (And When Each Makes Sense)

Campaign Budget Optimization (CBO) gets recommended by default, but it isn't always the right call. The choice between CBO and ABO should depend on what you're actually testing, not on which one is currently fashionable.

When CBO works well

CBO shines when your ad sets are genuinely similar in quality and you want the algorithm to find the best-performing audience automatically. It's efficient when you trust the algorithm to make smart allocation decisions across audiences that are all reasonably warm.

When ABO is the better choice

If you're deliberately testing very different audience types — say, a lookalike versus an interest-based audience — ABO guarantees each one gets a fair amount of spend to actually prove itself. Under CBO, a new or unproven ad set can get starved of budget before it has a chance to perform.

A practical middle ground

Many accounts do their creative and audience testing under ABO, then migrate winning combinations into a CBO campcampaign once there's enough signal to trust the algorithm's allocation. This gets you the best of both: fair testing conditions, then efficient scaling.

Neither approach is universally correct. The mistake is picking one and never questioning whether it still fits what you're trying to learn.