What the names mean
CBO stands for campaign budget optimization, the name Meta used when the feature launched. Meta's current name is Advantage+ campaign budget. Its help page says the feature is "also known as campaign budget, or budget with Advantage+ on". Media buyers still say CBO in conversation, and this page uses both names.
ABO stands for ad set budget optimization. Meta's help pages call it ad set budgets. Meta has no feature with the ABO label. The term is media buyer shorthand for the campaign setting where each ad set carries its own budget.
How each one works
With Advantage+ campaign budget you set one campaign budget, daily or lifetime, and Meta moves it toward "ad sets with the best opportunities" as the campaign runs. Meta warns that it "may not spend your budget equally for each ad set" and may put most of the budget on one ad set. For that reason Meta says to read results at the campaign level. You can set a minimum and a maximum spend per ad set. The ad sets must share the same budget type, the same bid strategy and, under the highest volume strategy, the same optimization event. Sales, leads and app promotion campaigns have it on by default, and a switch on or off needs at least two hours between changes.
With ad set budgets, each ad set spends its own budget "as soon as delivery opportunities become available". Meta also offers ad set budget sharing, which lets an ad set lend up to 20% of its daily budget to the others in the campaign.
Worked example
A campaign has three ad sets and $300 a day. Under ABO you give each $100. In a day they bring 10, 5 and 2 purchases, so the campaign CPA is 300 / 17 = $17.65, with ad set C at $50 per purchase.
Under CBO, Meta might spend $200, $80 and $20 on the same three ad sets. If that brings 20, 4 and 0 purchases, the campaign CPA is 300 / 24 = $12.50. Ad set C looks dead in its own row, which is why Meta says to judge the campaign, not the ad set.
Why it matters to a media buyer
The choice is control against efficiency. ABO guarantees each audience or creative gets its budget, which is what a clean test needs. CBO lets Meta chase the cheapest results, which is what a scaling campaign needs, at the cost of ad sets that get little spend and little data. A common pattern is to test under ABO and move winners into a CBO campaign.
In Adsap
The campaign and ad set builders support both settings, in the web app and from the AI copilot. The free ad set budget split calculator divides one daily budget across ad sets for ABO, equally or weighted. It also notes when Advantage+ campaign budget does the split for you. The docs' best practices page suggests CBO with at least $100 a day for 8 to 12 ad sets. For A/B tests it suggests separate ad sets with their own budgets.
Frequently asked questions
Yes. Advantage+ campaign budget is Meta's current name for campaign budget optimization. Meta's help page adds that it is also known as campaign budget, or budget with Advantage+ on.
Yes. Meta lets you set minimum and maximum spend limits for each ad set inside an Advantage+ campaign budget, for cases where an ad set has its own budget requirement.
Ad set budgets, so each variation gets the same spend and the comparison is fair. Once a winner is clear, a campaign budget can scale it with the other survivors.
Sources
- Meta Business Help Center, About Advantage+ campaign budget: "also known as campaign budget, or budget with Advantage+ on"; "may not spend your budget equally for each ad set". https://www.facebook.com/business/help/153514848493595
- Meta Business Help Center, About campaign budgets and ad set budgets: ad set budgets, spend limits per ad set, ad set budget sharing up to 20%. https://www.facebook.com/business/help/458847204894307
- Meta Business Help Center, Set up Advantage+ campaign budget: eligibility, on by default for sales, leads and app promotion, the two-hour minimum. https://www.facebook.com/business/help/343242619559352
- Adsap docs, best practices, and the ad set budget split calculator.