Determine how many impressions to book

The number of impressions you can book for a prospective line item depends on how willing you are to displace or preempt existing inventory.

First, run a forecast for the prospective line item (Learn how). Remember that your line item's trafficking criteria can greatly affect the number of available impressions.

How forecasting accounts for trafficking criteria

Forecasting takes most trafficking criteria into account when determining available inventory, but there are some details you should keep in mind:

Frequency capping

Frequency capping is considered. Because DoubleClick for Publishers uses a 28-day sample, monthly or lifetime frequency caps are not captured as part of the sample data. Consequently, in cases with monthly and lifetime frequency caps, forecasting can overpredict availability.


Forecasting looks at priority to determine the Reserved for lower-priority line items number--the number of impressions a line item can get if you’re willing to take impressions from lower priority line items. Priority is also taken into account when calculating impressions likely to deliver.

Delivery impressions (evenly, frontloaded...)

Forecasting ignores this delivery control. Instead, it optimizes delivery the best it can. For example, if a line item is set to deliver evenly, the forecast simulation might allocate impressions on a frontloaded basis. In some cases, this can lead to overly optimistic forecasts.


While cost is not a criteria considered in forecasts, you can view the revenue impact of competing line items.

Roadblock ads

When you run a forecast on roadblock ads, DoubleClick for Publishers records which impressions occurred together when a page is viewed--this is called page awareness. And forecasting takes into account the type of roadblock you're interested in booking, those set up to work with all of the creatives in the line item, or those that work with master/companion creative sets.

For example, a line item containing one creative that’s 728x90 and one that’s 300x250 has these forecasted page views in the following distribution:

  • Page A: the 728x90 creative serves 2 times without the 300x250,
  • Page B: the 300x250 creative serves 1 time without the 728x90, and
  • Page C: both creatives serve together (the roadblock) 4 times.
In this scenario, the forecasting simulation lets you know that 4 roadblock impressions are available, because it's aware that only Page C can serve the roadblock with both creatives.

For customers moving from Legacy DFP, note these differences in roadblock forecasting.

DFP Legacy and DoubleClick for Publishers use different assumptions when they forecast roadblock ads:

  • In Legacy DFP, only page views that were forecasted to accommodate all the ads in a roadblock counted toward forecast results. The predicted availability was further constrained to the lowest volume available to any one ad in the roadblock, based on the contending ads for different spots on those pages. However, when the roadblock actually served, the delivered impressions could exceed the forecasted amount due to pages where the master was eligible but not all of companions were.

  • DoubleClick for Publishers is page aware, so forecasts for roadblock creatives take into account only those impressions during which all the roadblock creatives render in the same page view. A single roadblock impression includes all the creatives in that roadblock.

Multiple creatives of the same size

If you have an ad with multiple creatives of the same size and you select the As many as possible setting for displaying creatives, you must enter the number of creatives of each size. Click the Provide some creative details link under the 'Inventory Sizes' field, then entering a number in the 'Count' field. Adding creative sizes and counts allows for better forecasting (more creatives mean more opportunities to serve to a given page), so it's optional, but recommended. If you don't include a creative count for each inventory size, forecasting will assume one creative per size.

Results on the first page of the forecast provide guidance that can help you decide how many impressions to book.

  • Available: These are impressions that match the line item’s targeting criteria and are currently free of obligations to other line items of any priority. Booking this number won't take impressions from other line items.

  • Reserved for lower-priority line items: These are impressions that can be safely displaced from line items at the same priority as the current line item or taken away from lower-priority line items. Doing so might negatively affect the delivery of these line items.

  • Unavailable: Impressions or clicks might be unavailable to this line item for the following reasons:
    • They're reserved for higher-priority line items.

    • They're reserved for same-priority line items that can't be displaced to other available inventory.

    • Restrictions apply, such as frequency capping for the prospective line item, competitive exclusions, ad exclusion labels, max creatives per page, roadblocking, and possibly others.
  • Matched for specified targeting criteria: The sum of "Available," "Reserved for lower-priority," and "Unavailable." This is the total number of impressions that would be available to the line item if it were unencumbered by other line items and any delivery restrictions, such as frequency capping.

You can also gauge and adjust the effect that booking the prospective line item would have on existing line items by clicking the View contending line items link. (Learn more)