CBO vs ABO is the choice between one budget for the campaign and one budget per ad set. CBO is what Meta now calls Advantage+ campaign budget: Meta shifts spend in real time to the ad sets with the best opportunities. ABO means ad set budgets: you decide what each ad set gets. Scale with CBO; control tests with ABO.
| CBO: Advantage+ campaign budget | ABO: ad set budget | |
|---|---|---|
| Where the budget sits | campaign | each ad set |
| Who splits spend between ad sets | Meta, continuously, towards the best opportunities | you |
| Spend per ad set | uneven by design: Meta may put most of it in one ad set | follows each ad set’s own budget |
| Control per ad set | optional minimum and maximum spend limits | you set each budget |
| Bid strategy | one for the whole campaign | can differ between ad sets |
| Label in a leads campaign | Advantage+ on | Advantage+ off, with two or more ad sets |
| Where Meta says to judge results | campaign level | ad set level |
| Best fit in lead gen | scaling ad sets you value the same | tests that need set spend; ad sets that differ in value, audience size or bid strategy |
With a single ad set the question goes away: Meta’s article on choosing a budget strategy says a campaign with one ad set works the same as an ad set budget.
What CBO and ABO are called in Ads Manager today
CBO stands for campaign budget optimization, the name Meta used before the feature became Advantage+ campaign budget. Meta’s own reporting article still says “previously known as campaign budget optimization”, and Ads Manager may label it Campaign budget or Budget with Advantage+ on. ABO is advertiser shorthand for the alternative, which Meta simply calls an ad set budget.
Meta’s article on campaign budgets and ad set budgets now lists three budget strategies:
- Advantage+ campaign budget: one campaign budget that “continuously distributes in real time to ad sets with the best opportunities”.
- Ad set budgets: a budget per ad set, which “can be spent as soon as delivery opportunities become available for that ad set”.
- Ad set budget sharing: you keep ad set budgets, but up to 20% of the daily budget moves between ad sets in real time, towards the better opportunities. It’s meant for campaigns that don’t use a campaign budget.
For the Leads objective you pick the budget strategy at campaign level, and Meta’s setup article says Advantage+ campaign budget is on by default for Sales, Leads and App promotion campaigns. In a leads campaign that choice also sets the Advantage+ label: several ad sets on their own budgets turn the budget lever to Advantage+ off. Advantage+ leads campaigns covers what else that changes.
One practical detail from the same article: Meta requires at least 2 hours between switching Advantage+ campaign budget on and off. If you need to undo it sooner, its advice is to pause the campaign and create a new one with ad set budgets.
How does campaign budget optimization on Facebook split spend?
Meta’s article About Advantage+ campaign budget says it plainly: the feature “may not spend your budget equally for each ad set”. With two active ad sets, Meta may put most of the budget into one of them if that’s how it gets the best overall result. The same article says it’s best suited to campaigns with at least 2 ad sets.
“Best overall result” has a precise meaning. With the Highest volume bid strategy, CBO goes after the most optimization events for the campaign as a whole, at the lowest average cost, and Meta tells you not to judge it by each ad set’s cost per result. Its worked example, simplified:
| Opportunities available | What CBO buys with $30 | |
|---|---|---|
| Ad set A | 4 results at $5 | 3 results, $15 |
| Ad set B | 6 results at $2 | 6 results, $12 |
| Ad set C | 3 results at $1, then one at $7 and one at $8 | 3 results, $3 |
| Campaign | 12 results, $2.50 each |
Half the budget goes to A, the ad set with the highest cost per result. Switch A off and the same $30 buys 11 results, because C’s cheap opportunities run out after three. Split the budget evenly, $10 per ad set, and it also buys 11. Meta’s point: a steady $5 beats a cheap start that turns expensive.
Two more behaviours from Meta’s CBO best practices shape a lead gen account:
- Audience size pulls budget. When audiences differ a lot in size, the ad sets with the largest audiences will likely receive the most budget.
- Pausing moves money. CBO spends on active ad sets only, so pausing one hands its share to the others, and the budget may be gone by the time you switch it back on. Meta also advises against pausing ad sets with low delivery.
The ad sets also have to match: the eligibility rules in the setup article require the same budget type and bid strategy across all of them, and with Highest volume the same optimization event. If one ad set needs a floor, CBO accepts minimum and maximum spend limits per ad set. Meta’s spend limits article recommends using as few as possible, calls a minimum “a target range, not a guarantee”, and warns that a cost per result goal or bid cap can make the minimum unachievable.
How do ad set budgets spend?
Each ad set spends its own budget whenever it finds opportunities, regardless of how the other ad sets are doing. Meta lists four situations where that’s the better choice:
- You want to control the amount spent on each ad set.
- The ad sets differ greatly in value and you can’t express that through manual bidding.
- Their audience sizes differ a lot.
- They use different optimization goals or bid strategies.
The fourth is a hard rule. Meta’s bid strategies FAQ says a campaign with Advantage+ campaign budget uses a single bid strategy, so a cost per result goal on one ad set and Highest volume on another means ad set budgets or two campaigns.
Ad set budget sharing sits in between: each ad set keeps its budget, and up to 20% of it can move to where Meta sees better opportunities. For a test that needs fixed spend per variant, leave it off.
CBO vs ABO for lead generation: tests and scaling
Testing creatives or audiences
A test needs every variant to spend enough to be judged. CBO is designed to do the opposite: concentrate spend where Meta sees results first. Put three new concepts in three ad sets under one campaign budget and one of them can take most of the money in the first days, before the other two have spent enough to tell you anything.
For tests, pick one of these setups:
- ABO with equal budgets, each sized in multiples of your target CPL. The Meta ads creative testing framework has the spend per creative and the decision rules.
- Meta’s A/B test, which splits the audience so nobody sees both versions and recommends the same budget for each (About A/B testing). Meta advises against testing informally by switching ad sets on and off.
- CBO with a minimum spend limit, when one ad set needs a fair share inside a scaling campaign. Meta’s own example is a brand entering a new market: without the minimum, the campaign budget may favour the established market’s cheaper short-term results.
Landing page tests are the exception. When two landing pages sit behind the same ad and the split happens after the click, the budget type has no say in it. That’s how landing page A/B testing works.
Scaling what already works
Once you have creative × landing page pairs under target, CBO is the better home for them. You raise one budget instead of several, spend follows whichever ad set is cheaper this week, and Meta’s minimum budgets article notes a lower risk of under-delivery, because budget moves freely across ad sets.
Two cautions. Changing the campaign budget can send several ad sets back into learning at once, depending on the size of the change, so scale in steps (how to scale Facebook ads has the weekly routine). And CBO treats the ad sets as equally valuable: Meta’s list of reasons to use a campaign budget includes “you value all ad sets the same”. If one ad set brings leads worth twice as much, give it its own budget.
| Situation | Budget type |
|---|---|
| One ad set | either: Meta says they work the same |
| Testing new concepts that each need set spend | ABO with equal budgets, or a Meta A/B test |
| Scaling proven pairs, same goal, similar audiences | CBO |
| A new region that needs a fair share inside a scaling campaign | CBO with a minimum spend limit |
| Ad sets whose leads are worth very different amounts | ABO, or separate campaigns |
| Different bid strategies per ad set | ABO, or one campaign per strategy |
| Audiences of very different sizes | ABO, or expect CBO to favour the largest |
Whichever budget type you pick, Meta reports per campaign or ad set, while your decisions are per creative and landing page. DropCPL syncs spend per ad from the Meta Ads API and counts leads on your own landing pages, so each creative × landing page pair gets a CPL from leads you actually received. Start free →
CBO vs ABO: does either change the learning phase?
No. Learning happens per ad set under both. Meta’s article on significant edits answers the CBO questions directly:
- initial learning takes the same time as with ad set budgets;
- CBO moving budget between ad sets doesn’t send them back into learning;
- a significant edit made at ad set level only affects that ad set;
- adding an ad set to a CBO campaign doesn’t reset the others;
- changing the campaign budget, or the campaign bid strategy, can send several ad sets back into learning at once.
What CBO can’t do is create budget. Ad sets usually exit learning after about 50 results in a week, and that threshold still applies to each ad set. Example: €3,000 a week at a €30 CPL buys about 100 leads. Split three ways under ABO, each ad set gets about 33 a week and none exits learning on schedule. Under CBO, Meta may concentrate spend so one ad set clears 50 while the other two starve. The structure is the problem in both cases: at that CPL, €3,000 a week supports two ad sets. The learning phase guide has the formula and the full list of edits that reset learning, and Facebook ads account structure shows how many ad sets per campaign and ads per ad set a lead gen budget supports.
Meta’s CBO best practices add two habits: add new ad sets in bulk, because the budget takes about 2 hours to re-adjust after each one, and enter campaign changes in bulk, so the campaign doesn’t re-enter learning once per change. They also note that the more ad sets and ads a campaign has, the longer it may spend in learning.
Why read results per creative × landing page, whatever the budget type
Meta’s advice on where to judge results is consistent. Its article on the breakdown effect says to evaluate at campaign level with Advantage+ campaign budget, and at ad set level when several ads run in one ad set. The A/B/C example shows why: an ad set that looks expensive on its own can be what keeps the campaign average down.
That’s the right way to judge Meta’s delivery. It’s the wrong level for the decisions you make: which creative to keep, which landing page to send it to, which pair deserves the next budget step. Example: a CBO campaign with two ad sets, €4,000 over two weeks, a €40 target CPL, leads counted on the landing pages and spend synced per ad.
| Ad set | Creative × landing page | Spend | Leads | CPL |
|---|---|---|---|---|
| Broad | Ad A × LP 1 | €1,500 | 60 | €25.00 |
| Broad | Ad B × LP 2 | €1,200 | 16 | €75.00 |
| Lookalike | Ad A × LP 2 | €900 | 18 | €50.00 |
| Lookalike | Ad C × LP 1 | €400 | 16 | €25.00 |
| Campaign | €4,000 | 110 | €36.36 |
The campaign sits under target at €36.36. So do both ad sets: Broad at €35.53, Lookalike at €38.24. Meanwhile Ad B × LP 2 costs almost twice the target after spending 30 times the target CPL, where a pair on target would have brought about 30 leads instead of 16. Both pairs above target send traffic to LP 2, and Ad A costs twice as much there as on LP 1, so the landing page is the first suspect. Neither the campaign view nor the ad set view shows any of it.
Keep Meta’s level for judging delivery, and make your own calls per pair, on leads you received, once a pair has spent enough to judge. CPL by creative shows how to join spend and leads per ad, and how to read the attribution matrix gives the spend thresholds before a cell means anything.