CBOCampaign Budget Optimization
CBO sets a single budget at the campaign level; Meta auto-distributes across ad sets based on real-time performance.
What does CBO actually mean?
Campaign Budget Optimization (CBO) is a Meta budget structure where you set a single budget at the campaign level rather than per ad set. Meta's algorithm distributes that budget across ad sets in real time, sending more spend to higher-performing ones.
CBO became Meta's default in 2019 and the only option for Advantage+ campaigns in 2023+. The advantage is automatic optimization: you don't manually rebalance ad set budgets. The trade-off is loss of control: under-funded ad sets can starve before they prove out, and CBO sometimes over-concentrates spend in one ad set.
ABO (Ad Set Budget Optimization), the older approach, sets budgets per ad set. ABO is still used for testing new audiences or creatives, where you want to guarantee each test gets enough spend to produce a signal. Most modern accounts run a hybrid: CBO for proven evergreen campaigns, ABO for tests.
Example
A brand creates a CBO campaign with $300/day total budget and 5 ad sets. Meta might allocate $150/day to the top ad set, $80 to the second, and $20 each to the rest based on performance.
When it matters
CBO is mandatory in Advantage+. ABO remains useful for early-stage testing where you need each cell to get enough spend to produce signal.
Related terms
ABO
ABO sets budgets at the ad set level rather than the campaign level. Used for testing where each ad set needs guaranteed spend to produce signal.
Advantage+
Advantage+ is Meta's AI-driven campaign suite (Shopping, App and Sales) that automates audience, placement and budget decisions.
Performance Max
Performance Max is Google Ads' AI-driven campaign type that serves across Search, Display, YouTube, Discover and Gmail from a single asset group.
Cost cap
Cost cap is a Meta bid strategy that limits maximum CPA. The platform spends as much as possible while keeping CPA at or below the cap.
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