Custom bidding overview and limitations

Use custom bidding to define a criteria for how much an impression is worth. Improve the cost-efficiency of your bids by allocating more value to impressions that align closer to your goals and less value to impressions that don’t.

You can gain granular control with custom bidding by creating algorithms that optimize toward your specific campaign goals. This helps better inform the bidding model Display & Video 360 uses to build the bidding strategy that's the right fit for your campaign.

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How it works

Custom bidding scripts and goals let you define the value of an impression that aligns with your campaign's goals.

Display & Video 360 uses the algorithm from your custom bidding scripts or goals to determine the score it assigns to impressions.

The outcome of previously scored impressions helps train the custom bidding model to help optimize your bidding strategy. You can use your custom bidding algorithm once it’s trained by assigning it to a line item.

Minimum data requirements

Custom bidding requires previously scored impressions within the advertiser to train a custom bidding model. You may have to wait several days before you can use custom bidding to meet the data requirements to train a bidding model.


Your custom bidding algorithm needs to meet the minimum data requirements to train before it's ready to serve. Assigning an untrained algorithm to a live campaign will cause your line item to stop spending.

Custom bidding uses impression data from the last 30 days of impressions to train your custom bidding algorithm.

If you pause custom bidding for more than 30 days, you may need to wait until you've met the data requirements to train your custom bidding algorithm.

Custom bidding scripts Custom bidding goals
  • At least 10,000 scored impressions and a minimum of 100-500 positively scored impressions for an advertiser.
  • At least 50 positively scored impressions for an individual line item.
  • Individual impression values must be greater than zero, and in the range of 0.000001 and 1,000,000.
  • Google Analytics goals require clicks. Make sure there's enough of data to generate a model.
  • A minimum of 100-500 positively scored impressions for an advertiser.
  • At least 50 positively scored impressions for an individual line item.

When to use custom bidding

While Display & Video 360 has standard automated bidding strategies that help you maximize performance and brand, custom bidding works best if you need advanced control over defining the value of an impression to customize a bidding strategy that goes beyond what automated bidding can do.

For example, you can optimize toward:

  • Brand key performance Indicators (KPIs): Such as viewability and video completions.
  • Conversion activities: Drive volume by assigning more weight to a higher value conversion event and a lower weight to an upper-funnel conversion event.
  • Custom Floodlight variables: Such as loyalty, products, and basket size.
  • Floodlight Sales revenue: By tracking the revenue parameter using Floodlight Sales tag.
  • Weighted conversions: Use Floodlight tracking activities that carry specific values to you depending on the product page visited.
  • Google Analytics 4 or Google Analytics 360 goals: You can link Google Analytics to Display & Video 360 to use goals and define weights to events on an advertiser’s site.
Note: For your custom bidding algorithm to score Google Analytics conversions, you'll need to:
Linking your Google Analytics account means that you're sharing conversion data with Display & Video 360, which is only available in custom bidding metrics through reporting.

Permission and access

Before you begin, check that you've the permission and access you need.

For algorithms created at the advertiser level:

  • You need partner level access or the specific advertiser level access to edit the algorithm.
  • You can’t share the algorithm with other advertisers.

For algorithms created at the partner level:

  • You need partner level access to edit the algorithm.
  • You can share the algorithm with multiple partners.
  • You can view the algorithm with advertiser level access, but can’t see which advertisers the algorithm is shared with.

Ways to use custom bidding

There are three ways to use custom bidding:

  • Creating a custom bidding goal: Define custom bidding goals to optimize impression values using simple weighted conversions without having to write script. Goals let you to assign value to impressions to build a custom bidding algorithm for your campaign goals.
  • Write a custom bidding script: Use basic knowledge of python to create custom bidding scripts that let you use first-party data to optimize impression values using non-conversion based goals, such as Brand Lift measurements.
  • Using the Display & Video 360 API: You can also use the Display & Video 360 API to create your custom bidding algorithms, upload and verify individual custom bidding scripts, and assign custom bidding algorithms to campaigns.
Note: You can have 10 active algorithms per advertiser ID at a time and archive inactive algorithms.

Once you create your custom bidding algorithm, you’ll need to keep your algorithm up to date and assign it to an insertion order or line item with future budgets.

Algorithms are suspended when:

  • The algorithm's script hasn't been updated or edited for 21 days.
  • There has been no spend associated with the algorithm for 21 days.
  • The algorithm isn't assigned to any insertion orders or line items that have future budgets or flights.

Evaluate the performance of custom bidding

It's a good idea to test your new algorithms before assigning them to a live campaign for the first time to optimize your return on investment. You can evaluate how your new custom bidding algorithm performs by using an A/B experiment to compare performance results with other algorithms when assigned to your campaign.

Once you assign your algorithm to a live campaign, you can also generate reports to understand how your algorithm performs toward your KPIs.

Custom bidding reporting

You can generate offline reports and view in-line metrics to evaluate how your custom bidding algorithm performs toward your KPI and cost.

You can use the following available metrics in your reports to evaluate custom bidding performance:

  • Impressions with custom value
  • Impressions with positive custom value
  • Total impression custom value
  • % impressions with positive custom value
  • Estimated total cost for impressions with custom value (advertiser currency)
  • Estimated cost per mile (CPM) for impressions with custom value (advertiser currency)
  • Impression custom value / cost
  • Impression value per 1000 impressions

You can view the full descriptions and learn more about metrics in reports.

Generate an offline report

You can set up an offline report by choosing the Standard report template, which includes the algorithm and algorithm ID dimensions.

You can select the impression custom value/cost and other available metrics to evaluate your algorithm's performance toward your KPIs given the cost.

Since an advertiser can have multiple algorithms at a given time, you can use the filters section to only include the specific algorithm you want to evaluate. Learn more about offline reporting.

View in-line custom bidding metrics

You can view performance metrics for all insertion orders and line items that use custom bidding.

View in-line custom bidding metrics

To view in-line custom bidding metrics:

  1. Go to Campaigns.
  2. Select the Insertion orders.
  3. Choose an insertion order.
  4. Use the drop arrow above the table and select Performance view.
  5. In Performance view, scroll the table to the right to view the Custom Bidding column.

Create a custom view for custom bidding metrics

To create a custom view that displays more custom bidding metrics:

  1. Go to Campaigns.
  2. Select the Insertion orders.
  3. Choose an insertion order.
  4. Use the drop arrow above the table and select Create new custom view.
  5. Under the Custom Bidding section, select the metrics you want to include.
  6. Select Apply.
Your algorithm needs to be active for 2 or more days to generate data for the report. Reports don't include data from the current and previous day due to the time it takes to record and score impressions.
Try choosing a date range. For example, select the last 7 days or chose the flight days of the campaign.

Custom bidding experiments

You can set up an A/B experiment to compare the total custom impression value between a new algorithm and other algorithms to determine how the new algorithm performs with different algorithms when assigned to a campaign.

Learn more about how to set up an experiment.


  • Custom bidding doesn't apply to YouTube, Gmail, Twitter, Audio, Tag Guaranteed, or Programmatic Guaranteed inventory.
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