If you have run ads on Meta, you will have come across the terms CBO and ABO (or you should have). These are two different ways of managing your ad budgets on Meta Ads, and choosing the right one can have a big impact on your results. Let’s look at what they mean, how they differ, and when to use each.

What CBO means

CBO stands for “Campaign Budget Optimisation”. With CBO, you set your budget at the campaign level, and Meta automatically decides how to distribute that budget across your different ad sets.

For example, if you set a daily budget of £100, Meta might give £70 to one ad set and £30 to another, depending on which is performing better at the time. The algorithm is designed to push more spend into the audiences or placements that are most likely to achieve your objective.

The main appeal of CBO is efficiency. Instead of you manually adjusting budgets for each ad set, Meta uses its data and machine learning to optimise in real time. Often, this means faster and more hands-off optimisation.

What ABO means

ABO stands for “Adset Budget Optimisation”. With ABO, you set your budget at the ad set level, which means you control exactly how much adset gets.

For example, if you have three ad sets and you want each to spend £30 per day, you can set this manually. Meta will spend that amount in each regardless of which ad set is performing best.

The main appeal of ABO is control. You get to decide where the money goes, rather than leaving it entirely to the algorithm. This often means, if you’re testing different audiences, you can ensure you’re comparing results in a fair test as often it’s hard to judge one adset versus the other if one has spent £50 and the other has spent £200.

The pros and cons of CBO

CBO can save a lot of time and usually works well for campaigns where your priority is efficiency. It is particularly useful when you have:

• Multiple ad sets targeting similar audiences

• Broad targeting strategies

• Limited time to monitor campaigns daily

• Limited budget to spread across adsets evenly

However, the downside is less control. If you want to guarantee that each ad set gets equal spend, CBO is not the right choice. Meta may push most of your budget into one ad set while neglecting others, even if you wanted to test them fairly.

Another note on this is that Meta will often show preference to the larger audiences. So, if you have tigher interest-based (detailed demographic) audiences within the same campaign as a broad audience or large LALs/LLAs (lookalikes), you’ll often find the latter 2 will receive most budget share (if not all budget).

The pros and cons of ABO

ABO gives you full control over budget distribution, which makes it great for testing. For example, if you want to see how three different audiences perform with the same budget, ABO lets you do that without Meta skewing the spend.

The downside is that ABO requires more management. If one ad set is performing really well, Meta will not automatically shift more money to it. You would need to spot this and adjust manually in your ongoing optimisation.

When to use CBO and when to use ABO

A good rule of thumb is:

• Use CBO for efficiency. When you are running a campaign at scale and want Meta’s algorithm to optimise towards the best results, CBO is usually the better option.

• Use ABO for testing. When you are trying out new audiences, creatives, or placements in different adsets and want to compare results fairly, ABO gives you the control you need.

Many advertisers start with ABO to test different strategies, then move to CBO once they know which ad sets are strongest.

Final thoughts

CBO and ABO are simply two different approaches to budget allocation in Meta ads. CBO prioritises efficiency by letting Meta decide where to spend, while ABO prioritises control by letting you set budgets manually.

Neither option is universally “better”. The choice depends on your campaign objective and how much control you want. For quick optimisation and scale, CBO is usually the winner. For testing and learning, ABO still has an important role.

The most successful advertisers often use a mix of both, testing with ABO and scaling with CBO. Understanding how each works will help you get the best balance between control and efficiency in your Meta ad strategy.