What are impressions, and how are they calculated?

First, a couple of definitions with a distinction. Downloads and impressions are linked, but they aren’t identical.

A download, according to the IAB definition, is a downloaded audio file that lasts at least one minute and has been filtered to exclude invalid and "bot" traffic and occurs in a single day. It doesn't matter what the duration of the complete podcast episode is; once one minute or more of the podcast has been downloaded, it counts as a download

On the other hand, an impression is defined by the IAB as an audio advertisement that has been downloaded within a podcast download.


  • A download is at least one minute of a podcast episode.
  • An impression is a full ad downloaded within a podcast download.
    • The number of impressions available to be sold in the future is also referred to as inventory (or Avails) in Dovetail Inventory.

And clients will want the most impressions they can get for their money. 

That being said -

How are impressions calculated in Dovetail Inventory? All signs point to your series’ forecast!

Is your podcast brand new? If the podcast is starting or has only been around for a brief time, the system looks at the Episode Drop Size and Episode Growth Step parameters - which are based on projections you would get from your Marketing, Sponsorship, or Sales teams.

The system then looks at the number of drafts created for the show, along with your podcast’s structure, to forecast how many impressions for your podcast might be available. For a podcast with published episodes, it’ll factor in the historic number of downloads, the scheduled drafts and show structure (you should create drafts for as far out as you plan on selling- selling for a season? Create a season of drafts!). 

The impression forecast in Dovetail Inventory looks like this and can be found within your series settings menu:forecasts_1.png

When a forecast for a flight is done, Dovetail Inventory looks at those avails against campaign flights that are already booked. The system will tell you the answer to the question you ask it, so know what question you are actually asking. The avails shown on the flight allocation table are based on what was put in for that flight: targeting rules, priorities, and zones. 

Another tool that is available to you is the Availability Search. The availability search is based on some of the same things but on a more generalized scale.  

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