CBO vs. ABO on Meta: Which Budget Setting to Use and When

CBO vs. ABO: The Short Answer

CBO (campaign budget optimization) means you set one budget for the campaign and Meta decides how much each ad set gets. ABO (ad set budget optimization) means you set a fixed budget on each ad set yourself.

For most brands, CBO should be the default. Use ABO when you have a real reason to control what each ad set spends, like a fixed budget for one market or ad sets that can't share a bid strategy.

If you can't find either term in Ads Manager, that's because Meta doesn't use them. CBO is now called Advantage+ campaign budget, which also shows up as "Campaign budget." ABO is just "ad set budgets." The old names stuck, so that's what everyone still says.

How CBO and ABO Compare

How CBO Works

You set one daily or lifetime budget. Meta moves it in real time toward the ad sets with the best opportunities, and spends less on the rest.

Meta is plain about what that means: the budget may not be split evenly, and with 2 active ad sets it might put most of the money into one of them.

That's the feature doing its job, and it's why Meta tells you to judge results at the campaign level. An ad set that looks expensive on its own may still be part of the cheapest overall result.

A few rules worth knowing, all from Meta's best practices and setup guide:

• Sales, Leads and App promotion campaigns have it on by default.
• It's best suited to campaigns with at least 2 ad sets.
• Every ad set needs the same budget type and bid strategy.
• Meta suggests staying at or under 70 ad sets per campaign. The limit is 200.
• A new active ad set can take about 2 hours for the budget to re-adjust.
• Audience size matters. Ad sets with the largest audiences will likely get the most budget.

How ABO Works

You give each ad set its own budget. Meta still decides who sees your ads and when, but it can't move money from one ad set to another.

The upside is control. If an ad set is set to $200 a day, it's aiming to spend $200 a day, whether or not it's your best one.

That's also the downside. Every budget is a decision you have to make and keep making. When one ad set starts working and another fades, nothing changes until someone logs in and moves the money.

ABO also spreads your results thinner. Here's a made-up example. Five ad sets at $100 a day with a $60 cost per purchase get about 12 purchases a week each. That's not much to judge an ad set on, and you'd be making budget calls off those small numbers every week.

There's Also a Third Option

Meta also has a middle setting: ad set budget sharing.

You keep your ad set budgets, but up to 20% of the daily budget can be shared with other ad sets in the campaign, adjusted in real time. If you're on ABO for a good reason and want a little flexibility, it's worth a look.

When to Use CBO

Use CBO when:

• All your ad sets are after the same result, like purchases.
• You value a purchase from one ad set about the same as a purchase from another.
• You're fine measuring the campaign as a whole.
• You'd rather spend your time on new ads than on budget edits.

That describes most brands running sales campaigns on Meta.

It's also what we see at the top end. We broke down three accounts spending $1M to $3M a month, and all three run CBO. None run ABO. That's only three accounts, so it's a pattern and not proof, but we're not seeing ABO on the other seven-figure accounts we have visibility into either.

The bigger reason is how Meta works now. Since Andromeda, Meta matches ads to people largely based on the creative itself. So the ad set matters less, and hand-setting a budget for each one buys you less. Your time is better spent on making ads that are actually different.

When to Use ABO

Meta's own list of when ad set budgets fit is a good one:

• You want to control the amount spent on each ad set.
• Your ad sets differ a lot in value, and bidding can't express it.
• Your audience sizes are very different.
• You have mixed optimization goals or bid strategies.

In practice, that looks like this:

1. A fixed budget for one market. Canada gets $500 a day no matter what, because that's what the business decided.
2. A small audience next to a large one. Under CBO, the large one will likely take most of the money. A customer list or a retargeting pool may need its own budget to spend at all.
3. Ad sets that aren't equal. One sells your high-margin product and the other sells a low-margin one. CBO only sees the results you told it to optimize for.

You can also use separate campaigns for these. If a market has a fixed budget, its own campaign keeps it out of the way.

Why We'd Skip "ABO for Testing, CBO for Scaling"

You'll see this advice everywhere. Test new ads in an ABO campaign so each one gets a fair budget, then move the winners to a CBO campaign.

We think it's a bad idea, for reasons we covered in testing vs. scaling campaigns. A winner is working where it is. Pausing it and relaunching it somewhere else doesn't bring the performance with it. And in practice the test campaign often ends up spending like a second scaling campaign anyway.

Forcing even spend also doesn't tell you as much as it seems to. In the three accounts we looked at, 10% to 30% of ads drive 70% to 80% of spend. Uneven spend is how Meta normally behaves, so a test that spends evenly looks nothing like the campaign the ad will have to win in.

What we recommend instead: keep one main CBO campaign, and put new ads in their own ad set inside it.

What to Do When CBO Starves an Ad Set

This is the fair complaint about CBO. You launch a new ad set, and Meta keeps sending the money to the ad set with your proven winners.

Work through it in this order:

1. Give it time. Spend moves around, and a new ad set needs a chance to find its footing.
2. Check for a delivery problem. A tight cost goal can choke delivery on its own.
3. Don't pause the ad sets with low delivery. Meta warns this can raise your cost per action on the ones still running. Pausing and unpausing can also mean there's no campaign budget left when the ad set comes back.
4. Set a modest minimum spend limit on the new ad set. That guarantees enough spend for a real read.

Meta says to use ad set spend limits sparingly, and to be especially careful pairing them with cost or bid controls, because too many constraints can stop delivery. We agree. One small minimum on one new ad set is fine. Limits on every ad set are ABO with extra steps, and at that point Meta suggests you just use ad set budgets.

We walk through the full fix in why new Meta ads don't get spend.

Common CBO Mistakes

• Judging each ad set on its own. Look at total results and average cost for the campaign first.
• Adding ad sets one at a time. Meta recommends adding them in bulk, and making setting changes in bulk, so the campaign spends less time in the learning phase.
• Setting the budget too low for your cost goal. With a cost per result goal, Meta says your daily budget should be at least 5 times that goal. A $40 goal needs at least $200 a day. If you don't have a goal yet, start with your break-even number.
• Panicking about daily spend. Meta says spend can run up to 75% over your daily budget on some days and lower on others. That flexibility is rolling out gradually, and the weekly total won't go past 7 times the daily budget.

For more on how big accounts behave, our Meta Ads Statistics hub has the data in one place.

How We Work With CBO and ABO at Biddyco

We're a creative agency for Meta ads, so the budget setting matters to us for one reason: it changes how we plan creative. In a CBO campaign, new ads have to earn their spend, so each batch has to bring genuinely different ideas.

Our US-based senior team works across 100+ accounts and $20M+ in monthly spend. New files land every 2 to 4 weeks, and we aim for one round of feedback.

If you need more ads worth testing, talk to us.

FAQ

What does CBO stand for?

CBO stands for campaign budget optimization. Meta now calls it Advantage+ campaign budget, and you may also see it labeled "Campaign budget." You set one budget and Meta splits it across your ad sets in real time.

What does ABO stand for?

ABO stands for ad set budget optimization. It's an advertiser term, not a Meta one. In Ads Manager, it simply means using ad set budgets, where each ad set has its own fixed budget.

Is CBO better than ABO?

For most brands, yes. CBO moves money to the best opportunities without anyone touching it, and it's Meta's default for Sales, Leads and App promotion campaigns. ABO is better when you need to control what each ad set spends.

Should I use ABO or CBO for testing?

We'd test inside your main CBO campaign, with new ads in their own ad set. That avoids moving winners later. If the new ad set gets starved, set a modest minimum spend limit on it.

Does CBO matter if I only have one ad set?

Not much. With one ad set, the whole budget goes to it either way. Meta says the feature is best suited to campaigns with at least 2 ad sets.

Can I switch from ABO to CBO on a live campaign?

Yes. Meta lets you turn on Advantage+ campaign budget by editing an existing campaign, as long as your ad sets meet the requirements, like sharing a bid strategy. There's a 2 hour minimum between switching it on and off. Treat it as a real change and expect results to move around.