What is Advantage campaign budget?

Advantage campaign budget is a Meta setting that replaces separate ad set budgets with one campaign budget, which Meta moves in real time toward the ad sets with the best opportunities. It was formerly known as campaign budget optimisation, or CBO. Ads Manager now labels it Advantage+ campaign budget, or simply campaign budget, and Meta's developer documentation still uses the name Advantage campaign budget. It works with a daily or lifetime budget.

Spend across ad sets is uneven by design, so Meta says to judge results at campaign level. Meta says it suits campaigns with at least two ad sets, and an Advantage+ sales campaign needs it switched on. A large change to the campaign budget can send several ad sets back into the learning phase.