Campaign budget optimisation (CBO) automatically manages your campaign budget across ad sets to get you the overall best results. With CBO, you set one central campaign budget. This budget continuously distributes in real time to ad sets with the best opportunities, throughout the course of your campaign.

How it works

Instead of setting individual ad set budgets, you set one overarching campaign budget. This budget has flexibility to spend more on ad sets with the best opportunities, and less on underperforming ad sets. The amount that you set can apply to each day the campaign runs (daily budget), or over the lifetime of the campaign (lifetime budget). If you use a lifetime budget, you can choose to run ads on a schedule. In that case, CBO works even if your active ad sets have different start and end times.

CBO may not spend your budget equally for each ad set. For example, if you have two active ad sets in your campaign, we might spend 90% of your budget on one ad set if that’s how we can get the overall best results. Therefore, when you use CBO, it’s important to analyse results at the campaign level, rather than at the ad set level.

Campaign budget optimisation can help if you want to:

  • Set a campaign budget with flexibility in how that budget is spent across ad sets.
  • Get the most results possible from your campaign, at the lowest cost.
  • Simplify campaign setup and reduce the number of budgets that you have to manage manually.

Set up campaign budget optimisation

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Campaign budget optimisation (CBO) lets you set one central campaign budget that continuously distributes in real time to ad sets with the best opportunities, throughout the course of your campaign. You can set up CBO during campaign creation, or edit your existing campaign to turn CBO on.

To set up campaign budget optimisation during campaign creation:

  1. Turn on the campaign budget optimisation toggle.
  2. Choose whether you want your campaign budget to be a daily budget or lifetime budget.
  3. Set a budget amount.
  4. Choose a campaign bid strategy.
  5. If you use a lifetime budget, you can choose to run ads on a schedule. You’ll set the specific schedule within each ad set.

Note: There’s a required two-hour minimum time limit when switching campaign budget optimisation on or off. If you need to turn off campaign budget optimisation and you turned it on less than two hours ago, you can choose to pause the campaign and create a new one with ad set budgets.

Eligibility requirements for campaign budget optimisation

To use campaign budget optimisation, your campaign must have:

  • The same budget type for all ad sets (lifetime or daily).
  • The same bid strategy for all ad sets (lowest cost, lowest cost with bid cap or cost cap).
  • The same delivery optimisation event for all ad sets, if the bid strategy is lowest cost.
  • Standard delivery type selected for all ad sets.

Note: When using campaign budget optimisation, you can include more than 70 ad sets (but no more than 200) in a single campaign. However, you’re limited by what edits you can make after you publish. Learn more about using CBO for campaigns with 70+ ad sets.

Best practices for campaign budget optimisation

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When using campaign budget optimisation (CBO), we recommend the following best practices to boost your campaign effectiveness.

  • Don’t exceed 70 ad sets per campaign. If you include more than 70 ad sets in your campaign, you’re limited by what edits you can make after you publish. Remember that the more ad sets and ads in a campaign, the longer it may spend in the learning phase.
  • After your initial setup, add additional ad sets in bulk. Whenever you add a new active ad set to your campaign, it can take about two hours for CBO to re-adjust.
  • Don’t manually pause and unpause your ad sets. CBO reserves and spends your campaign budget on active ad sets, and pausing an ad set removes it from consideration. For example, if your campaign budget spend is for two ad sets, pausing one ad set would cause our system to focus on spending the budget entirely on the active ad set. By the time you unpause the other ad set and it starts to run, there might not be any budget left in the campaign.
  • Use ad set spend limits sparingly, or not at all. The more budget that’s locked into specific ad sets, the less flexibility our delivery system has to optimise your campaign budget. Be especially careful if you use a cost or bid control along with ad set spend limits, because too many spend constraints can cause your ad set to deliver less than it should, or not deliver at all. If you have strict budget requirements for each ad set in your campaign, you may want to consider using ad set budgets instead of CBO. Learn more about how to choose between campaign budgets and ad set budgets.
  • If you adjust campaign settings, input changes in bulk to minimise time spent in the learning phase. If you input changes one at a time, your campaign may have to re-enter the learning phase each time.
  • Remember that audience size may affect budget distribution. If your audiences are significantly different in size, ad sets with the largest audiences will probably receive the most budget with CBO.
  • Don’t pause ad sets with low delivery. CBO distributes budget to maximise all available opportunities, and pausing a low-delivery ad set today prevents CBO from finding tomorrow’s opportunities. This can ultimately cause an increase in cost per action (CPA) for your active ad sets.
  • Ensure that all ad sets in your campaign can be delivered. If an ad set isn’t delivering, it isn’t encountering any opportunities for results, and we can’t distribute budget to it. Instead of pausing ad sets with low delivery, learn more about how to identify and troubleshoot delivery issues with CBO.
  • Analyse results at the campaign level, rather than at the ad set level. To understand campaign budget optimisation results, pay attention to the total number of optimisation events for your campaign and the average cost per optimisation event at the campaign level.

About ad set spend limits with CBO

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Minimum and maximum ad set spend limits are available with campaign budget optimisation (CBO). However, we recommend using the lowest number of spend limits, because they can prevent CBO from taking advantage of the best opportunities available. Instead, use cost and bid or return on ad spend (ROAS) controls to express ad value while maintaining spend flexibility.

Spend limits may be useful if:

  • You have specific budget requirements for an ad set. In this case, you may want to use an ad set budget. Learn more about how to choose between campaign budgets and ad set budgets.
  • You’re using the lowest cost campaign bid strategy and don’t know the value of reaching a given audience.

For example, imagine you have two ad sets to promote a brand. One ad set is for people in California, where you have a strong brand presence. The other ad set is for people in New York, where you haven’t established your brand yet. If you’re using the lowest cost bid strategy to help assess the value of this new market, a minimum spend limit might be helpful. Without a minimum spend limit, CBO may spend more budget on your California ad set to get the most efficient short-term results. This is because CBO finds the lowest-cost opportunities in real time. However, you wouldn’t be able to explore your longer-term spending options in New York.

Note: If your active ad sets use spend limits, we recommend caution when changing your campaign budget. Remember that if you turn off CBO, your spend limits will be reset.

Using maximum spend limits

A maximum spend limit is a hard cap on how much we can spend on an ad set. We stop spending once we reach your ad set’s maximum limit, even if your overall campaign budget is higher. When using maximum spend limits:

  • Use caution when pausing or deleting ad sets. When you pause or delete ad sets, your total maximum spend may be less than your total campaign budget.
    • For example, imagine that you have a campaign with a USD 50 budget and five ad sets each. If you set a maximum spend limit of USD 10 for each ad set, that would make your total maximum spend limit USD 50. However, if you paused one of the ad sets, your total maximum spend would decrease to USD 40. Even though your overall campaign budget would remain USD 50, we’d now spend up to USD 40.
  • Increase your maximum spend limit if you increase your campaign budget. We can’t spend your updated campaign budget if we’re limited to your ad set’s original maximum spend limit.
    • For example, imagine you have a campaign budget of USD 50 and a maximum ad set spend limit of USD 50. If you increase your campaign budget to USD 60 without also increasing the ad set spend limit, we can’t use that additional USD 10.
  • Make sure your maximum spend limit is at least USD 1 (USD) when using daily budgetlowest cost or impressions as the metric by which you get charged.

Using minimum spend limits

A minimum spend limit is a target range, not a guarantee. It tells us the lowest range of how much we should spend on an ad set. When using minimum spend limits:

  • Decrease your minimum spend limit when you decrease your campaign budget. Your minimum spend limit must be the same or less than your campaign budget. Otherwise, we can’t meet your minimum spend limit.
    • For example, if you have a campaign budget of USD 50 and a minimum spend of at least USD 20, that means we can’t spend less than USD 20 on your ad set. However, if you decrease your campaign budget to USD 10, we wouldn’t be able to meet your minimum spend limit of USD 20. You’d have to also decrease your minimum spend limit to USD 10 or less.

Using both minimum and maximum spend limits

We don’t recommend adding both minimum and maximum spend limits to an ad set at the same time. Using both constraints can limit how we can distribute your budget, which may lead to a higher cost per action, lower return on ad spend or underperforming delivery. When using minimum and maximum spend limits at the same time:

  • Make sure there’s at least a 0.9% difference between them.
  • Make sure there’s at least a difference of USD 1 between them.

Note: It takes up to 15 minutes after publishing for spend limit edits to take effect.

About using CBO for campaigns with 70+ ad sets

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Note: The number of ad sets you have includes active and inactive ones.

When using campaign budget optimisation (CBO), you can include more than 70 ad sets (but no more than 200) in a single campaign. However, you’re limited by what edits you can make after you publish it.

Campaigns with CBO turned on

If your campaign has more than 70 ad sets and uses CBO, you can’t update the following settings after you publish it:

  • Turn off CBO
  • Edit the delivery type
  • Edit the campaign bid strategy

If your campaign has fewer than 70 ad sets, you can edit those settings after you publish your campaign.

Note: To change these settings in your published campaign, duplicate the campaign or ad set and then publish. However, this may re-enter the learning phase.

Campaigns with CBO turned off

If your published campaign has more than 70 ad sets and isn’t using CBO, you can’t turn CBO on without decreasing your ad sets.

Once your campaign has fewer than 70 ad sets, you can update your settings, turn CBO on and publish. Then, duplicate any removed ad sets back into your campaign. You can also create a new campaign.

Campaigns that exceed 200 ad sets

When using CBO, the maximum number of ad sets for any single campaign is 200 (including active and inactive campaigns). If you have 200 ad sets, you won’t be able to duplicate or add any ad sets into the campaign.

To create space, you can either delete ad sets or duplicate them into a new or existing campaign and then delete them in the original campaign.

Understand campaign budget optimisation results

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Campaign budget optimisation (CBO) automatically manages your campaign budget across ad sets to get you the overall best results. Use the following best practices when analysing results for CBO.

  • Look at results for your campaign as a whole, not for individual ad sets. To analyse CBO performance, look at the total number of results for your campaign and the average cost per optimisation event at the campaign level.
    • CBO aims to get you the best results overall and may not spend your budget equally for each ad set. For example, if you have two active ad sets in your campaign, we might spend most of your budget on one ad set if that’s how we can get the overall best results.
    • If you only look at results for individual ad sets, it may seem like CBO is spending more budget on ad sets with a higher cost per optimisation event. However, this doesn’t take into account the cost of optimisation events across all of your ad sets and how costs changed over time. Learn more about how CBO distributes budget with the lowest cost bid strategy and why it can be misleading to only consider spend for individual ad sets.
  • Remember that it’s normal to see some fluctuation in spend. For example, daily budgets are an average and may fluctuate up to 25% above or below your budget on a given day. If you use a lifetime budget, we may spend more on days when better opportunities are available and less on days with fewer opportunities. The delivery system also predicts the best times throughout the day to deliver ads according to your optimisation objectives. That means that it’s usually normal for delivery to be focused within a certain period of the day. If you think you’re seeing more than this normal fluctuation, check whether:
    • Your ad sets are in the learning phase. Ad performance is typically less stable during the learning phase. In Ads Manager, the Delivery column reads “Learning” when an ad set is in the learning phase.
    • Settings within your campaign, ad set or ad are constraining delivery. Constrained delivery can cause results to slow down or even stop entirely. Learn more about how to identify and troubleshoot delivery issues with CBO.
    • Your budget or schedule was changed near the end of the day. If you change your budget or schedule near the end of the day, the system may not have enough time to apply new settings. For example, if you decrease your daily budget from USD 200 to USD 100 at 17:00, the system may have spent over your new daily budget of USD 100 already.
  • Remember that it’s normal for a campaign’s average cost per optimisation event to increase over time. The delivery system seeks the lowest cost opportunities first. When those lower cost opportunities run out, the system may move on to more expensive options, depending on your bid strategy. This means that you may see costs increase over the schedule of your campaign.
  • Be careful when using specific result breakdowns. For example, if you break down the results of your campaign by hour, you may see performance oscillations that average out over time. Try using result breakdowns at the campaign level over the course of a full week. You can also try viewing results with no breakdowns at all to understand the overall performance of your campaign.
  • Remember that your audience size and optimisation choice can affect budget distribution.
    • If your audiences are significantly different in size, ad sets with the largest audiences will probably receive the most budget with CBO.
    • When you use the lowest cost bid strategy, ad sets optimised for events that are easier to achieve may receive more budget with CBO. This is because they offer more opportunities for results. For example, landing page views may be easier to achieve than purchase events. If you optimise one ad set for landing page views and one for purchases, the ad set optimised for landing page views may offer more opportunities for results at a lower cost. Therefore, it might receive more budget if you use CBO with the lowest cost bid strategy.

    Understand campaign budget optimisation reporting when using the lowest cost bid strategy

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    Summary

    You shouldn’t judge how campaign budget optimisation distributes your budget based on the average cost per optimisation event for each ad set and how much we spent on it. You should judge it based on the total number of results for your campaign and the average cost per optimisation event at the campaign level.

    Context

    When viewing the results of a campaign that used campaign budget optimisation and the lowest cost bid strategy, you may see some numbers that are different from what you expected. This article explains what these results actually indicate, and why you shouldn’t worry that campaign budget optimisation isn’t working properly.

    • Campaign budget optimisation and the lowest cost bid strategy help you get the lowest cost per optimisation event for your campaign overall, not for any given ad set.
    • The lowest cost bid strategy always goes after the lowest-cost optimisation events available. However, over time, as the inexpensive ones are exhausted, we have to start spending on more expensive optimisation events to continue spending your budget. (These “more expensive optimisation events” are still the lowest-cost optimisation events available at that time.)
    • The amount of optimisation events and ratio of “inexpensive” to “expensive” (these descriptions are relative to the type of campaign you’re running) optimisation events varies from ad set to ad set. Some may have a few very inexpensive optimisation events and many very expensive optimisation events. Others may have a lot of moderately expensive optimisation events.

    Example

    Here’s a simplified example that shows how campaign budget optimisation spends your budget and why the reporting on the amount spent on each ad set might be confusing at first.

    Important: Bear in mind that you won’t have information on things such as the total number of opportunities for each ad set or how much each result costs when actually running and analysing reports on your campaigns.

    Say that there are 15 opportunities to show your ad:

    • Four for ad set A
    • Six for ad set B
    • Five for ad set C

    The opportunities for A cost GBP 5 each. The opportunities for B cost GBP 2 each. Three opportunities for C cost GBP 1, one costs GBP 7 and one costs GBP 8. You have a campaign budget of GBP 30.

    Campaign budget optimisation would get you:

    • 12 optimisation events for GBP 30
    • An average cost per optimisation of GBP 2.50 for your campaign

    Here’s how those results would break down at the ad set level:

    • A: Three optimisation events for GBP 5 each (GBP 15 of total spend)
    • B: Six optimisation events for GBP 2 each (GBP 12 of total spend)
    • C: Three optimisation events for GBP 1 each (GBP 3 of total spend)

    At this point, as you wouldn’t know about the other, more expensive opportunities our system avoided, you might wonder: Why did you spend so much on the ad set with the highest average cost per optimisation event and so little on the ad set with the lowest? You might even be tempted to turn off ad set A or campaign budget optimisation itself.

    Here’s why turning off ad set A isn’t a good idea. Given the same set of opportunities but with ad set A turned off, you’d get:

    • 11 optimisation events for GBP 30
    • An average cost per optimisation event of GBP 2.73 for your campaign

    Here’s how those results would break down at the ad set level:

    • A: No results
    • B: Six optimisation events for GBP 2 each (GBP 12 of total spend)
    • C: Five optimisation events for an average of GBP 3.60 each (GBP 18 of total spend)

    This shows how, by taking the optimisation events available to A, we avoided having to take the even more expensive optimisation events available to C. C has inexpensive initial optimisation events available, but it quickly gets much more expensive to spend money on it. A has more expensive initial optimisation events, but its cost per optimisation event is more stable. This makes A a better choice for budget distribution over time, which means we’ll spend more money on it overall.

    Here’s why turning off campaign budget optimisation altogether isn’t a good idea either. For the sake of simplicity, let’s assume you divided your GBP 30 campaign budget evenly between your three ad sets, giving each one a GBP 10 budget. Here are the results that would be produced for the same set of opportunities:

    • 11 optimisation events for GBP 30
    • An average cost per optimisation event GBP 2.73 for your campaign

    Here’s how those results would break down at the ad set level:

    • A: Two optimisation events for GBP 5 each (GBP 10 of total spend)
    • B: Five optimisation events for GBP 2 each (GBP 10 of total spend)
    • C: Four optimisation events for an average cost of GBP 2.50 each (GBP 10 of total spend)

    Troubleshoot campaign budget optimisation

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    If you’re using campaign budget optimisation (CBO) and your campaign isn’t delivering as expected, you may have non-optimal settings within your campaign, ad set or ad. This guide will help you troubleshoot your campaign in Ads Manager.

    Note: It’s important to understand how CBO works so you can identify what normal performance looks like, and when you need to troubleshoot. Learn how to understand campaign budget optimisation results.

    This guide covers three scenarios:

    • My campaign isn’t running: None of my budget has been spent and my ads aren’t getting any impressions at all. Learn more.
    • My campaign hasn’t delivered enough since it started: I’m not spending enough to meet my daily or lifetime budget goals. Learn more.
    • My campaign slowed down or stopped: My ads were delivering normally, but now I’m spending less and getting fewer or no impressions. Learn more.