# What is ABO (ad set budget optimisation)?

> ABO means you set a budget on each Meta ad set instead of the campaign. How it works, when it beats CBO for testing, and a worked example with rupees.
- **Author**: Marxx
- **Published**: 2026-11-03
- **Category**: Meta
- **URL**: https://marxx.ai/library-glossary/abo

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ABO (ad set budget optimisation) means each ad set has its own budget, so you decide how much each audience or idea gets. It is the other choice to [Advantage+ campaign budget](/glossary/advantage-campaign-budget) (CBO), where Meta splits one campaign budget for you. Meta's own name for it is "ad set budgets".

## How it works

Meta says you can set an overall budget on the campaign, or set separate budgets on your ad sets (Meta Help Centre, checked 2026-10-20). With ad set budgets, each ad set spends its own money. Meta does not move it between ad sets, apart from the optional budget sharing described below.

Meta suggests ad set budgets when you want more control over delivery, when ad sets have mixed goals and bid strategies, or when audience sizes differ a lot.

A daily budget is an average. Spend can run up to 75% above it on some days, and a week will not pass seven times the daily budget.

## A worked example

Say you test 3 hooks, one per ad set, at INR 1,500 a day each. After 6 days each has spent INR 9,000.

| Ad set | Purchases | Cost per purchase |
|---|---|---|
| Hook A | 18 | INR 500 |
| Hook B | 11 | INR 818 |
| Hook C | 22 | INR 409 |

Each hook got an equal chance, so the gap means something. With one shared campaign budget, Meta could have sent most of the money to hook C early, and hook B would never have had a fair run.

## When to use it

- You are testing audiences or ideas and want equal spend.
- One audience is tiny, such as retargeting, and a shared budget would overfeed it.
- You need to cap spend on a specific ad set.

Switch to campaign budget when you want to scale what already works. See [CBO vs ABO](/compare/cbo-vs-abo).

## Watch the learning phase

Many small ad sets can each get too few results. Meta says ad sets usually leave the [learning phase](/glossary/learning-phase) after about 50 results in the week after the last significant edit. Four ad sets at INR 500 a day may each learn slowly. Merge them if so.

Meta also offers ad set budget sharing. An ad set can share up to 20% of its daily budget with others, for campaigns not using a campaign budget.

## FAQ

### Is ABO outdated?

No. Meta still offers ad set budgets, and they are the usual choice for clean tests.

### Can I mix ABO and CBO in one campaign?

No. A campaign uses either one campaign budget or separate ad set budgets.

### What is the difference between ABO and an ad set?

An ad set is the level of the campaign that holds audience and placements. ABO means that level also holds the budget.

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