Compare Future sell-through reports and line item forecasts

Why Ad Manager "Check inventory" forecasts differ from Future sell-through reports

In Google Ad Manager, there are two main ways to predict availability:

  • Line item forecasts appear when you click Check inventory when creating or viewing a line item and provides a forecast focused on a single line item. This can help you maximize the number of impressions for that particular line item and targeting.
  • Future sell-through reports are a report type that displays availability across your entire Ad Manager network. Future sell-through reports can help you determine whether you have space to book more line items.

Summary of differences

The table below summarizes differences between interactive forecasting and future sell-through reports. Note that there might be additional differences in behavior not covered here.

  Check inventory forecast Future sell-through report Possible discrepancies

Manual and historical adjustments taken into account.



Booked line item data freshness

Up-to-the minute


Future sell-through reports are more likely to overestimate available inventory due to activity since the report was started.


The line item's "Creative count" can significantly affect forecast.

To more accurately compare results, click Target creatives and help forecast available inventory under "Inventory sizes" and specify a high number of creatives in the "Count" field, such as 10.

Line item forecasts account for serving restrictions such as frequency capping and roadblocks. For example, if the creative details specify it can fill only one ad slot on a page (which is the default), this will reduce the available impressions.

The line item's "Creative count" is not considered. 

There's no proposed line item with a limited number of creatives, so the sell-through report can't apply any of the restrictions and will assume that all available ad slots can be filled.

Future sell-through reports might show more availability than interactive forecasting.

Maximum look ahead

Two years

90 days for daily-granularity data; 1 year for monthly granularity data.

Special ad units

Impressions from special ad units are generally excluded while computing forecasted impressions. This includes impressions from special ad units that are parts of placements or for which parent ad units are targeted. The exception is when special ad units are explicitly targeted in the line item.

Special ad units are taken into account for inventory projections.

In check inventory, special ad units must be explicitly targeted.

In future sell-through, they might be implicitly targeted through parent ad units or placements.
Simulation Simulation is run for the time period of the proposed line item. Simulation is run for 18 months For competing line items with date ranges that extend outside the time window being forecasted, Ad Manager estimates the number of impressions that will compete.


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