Campaign Budget Optimization (CBO) implicit budget floors

Campaign Budget Optimization (CBO)

Facebook's Campaign Budget Optimization (CBO) automatically distributes a total campaign budget across various ad sets to optimize for the lowest cost per result. This mechanism relies on an internal pacing algorithm to shift spend toward higher-performing audiences.

While CBO is designed to improve efficiency for various workloads, there is no explicit public documentation regarding the minimum daily budget required to sustain consistent delivery. When budgets are set near the implicit floor—approximately $1 USD per day—delivery patterns often become erratic, and the relationship between these low budgets and the learning phase requirements remains undefined.

What is the documented minimum daily budget required for CBO to maintain stable delivery? How does the pacing algorithm handle spend allocation when the total budget is insufficient to meet the standard learning phase data thresholds?