Podtrac Measurement, Verified by IAB Tech Lab

IAB Podcast Measurement Technical Guidelines Version 2.0 Details

 Podtrac announced today that its measurement system has been given an official “seal of approval” by the IAB Tech Lab as compliant with the IAB Podcast Measurement Technical Guidelines Version 2.0.  Podcast audience counts for any publisher or podcast provided by Podtrac’s redirect measurement system, including those listed in its dashboard and its monthly Podcast Industry Rankings, are verified compliant through the IAB Tech Lab program.The IAB Public Disclosure for Podtrac is available here.


Since 2005, Podtrac has provided independent podcast measurement for any podcast, publisher or network, regardless of where they choose to host their podcast episode files, to thousands of podcasts including the majority of top podcast publishers.  In 2016, the IAB Podcast Working Group, comprised of more than 40 member companies, including podcast publishers and hosting companies, developed the IAB Podcast Measurement Technical Guidelines Version 1.0 published in 2016 and the Version 2,0 guidelines published in 2017. The IAB Tech Lab Podcast Measurement Compliance Program process is an opt-in initiative, and includes a rigorous audit of systems and technologies used to produce counts consistent with the guidelines.  

 Certification Details

Per the IAB Tech Lab Podcast Measurement Compliance Program, Podtrac is the first company to be verified by the Tech Lab for:

  1. Counting podcast audiences through a measurement redirect. Verified audience counts for any podcast measured by Podtrac are available from Podtrac regardless of where the podcast files are hosted.

  2. Identifying multiple podcast audience members behind shared IP addresses.  A significant percent of podcast audiences access podcasts in shared IP environments, such as mobile network NATs and corporate firewalls. Podtrac’s advanced systems and analysis count unique individuals in these scenarios.  

For those interested in more details, below is more information about each of these topics.

1- Counting podcast audiences through a measurement redirect 

Podtrac’s redirect measurement system is certified as following the guidelines’ goals of excluding download counts having less than a minute of downloaded content.

The Challenge

Before Podtrac, the IAB Tech Lab had not given a compliance seal to any company for counts and analysis gathered through a measurement redirect.  That’s because a key challenge is removing counts for podcast downloads that don’t achieve the Version 2.0 guideline’s minimum 1-minute file threshold level as described in server log files, and standard redirect measurement systems don’t have access to this data.  Podtrac’s previous system accounted for partial downloads, but the guidelines provide an option which encourages innovation to employ “a more sophisticated mechanism.”  

The Solution

Podtrac developed a new proprietary system released as part of our algorithm updates on June 1, 2019 that provides an accurate measure of partially downloaded podcast files. Per the Version 2.0 guidelines, Podtrac uses more advanced algorithms that factor in a correction for partially downloaded content than the example process listed. Podtrac uses advanced algorithms to identify and remove partial downloads in real time using data captured through its redirect.  Podtrac disclosed the complete details of its process and analytics to the IAB Tech Lab and an independent technical auditor, and after a rigorous review, they agreed that this produces counts for partial downloads consistent with the guidelines.

 What this means to publishers and advertisers

Podtrac solved the critical task of accurately removing partially downloaded podcast files that don’t achieve the minimums specified in the Version 2.0 guidelines using a redirect measurement system, by developing a new method that achieved certification.  

Now, with Podtrac:

  • Any publisher can access verified audience counts for their podcast today regardless of where they host their episode files by using the Podtrac redirect.

  • The industry has a podcast industry ranking with audience counts officially deemed compliant with the IAB Podcast Measurement Technical Guidelines Version 2.0.

 As of today, Podtrac is the only podcast company using a measurement redirect to have addressed the partial download requirement to the satisfaction of an independent auditor and the IAB Tech Lab, which means that when it comes to redirect podcast measurement systems, only counts from Podtrac are verified as compliant with the Version 2.0 guidelines.

 2 - Identifying multiple podcast audience members behind shared IP addresses. 

Podtrac’s algorithms for counting downloads from multiple users with the same device types and client software behind shared IPs are certified as consistent with the guidelines.

The Challenge

Podcast publishers and advertisers have asked if we can identify multiple users behind shared IP addresses such as corporate firewalls and mobile networks.  Increasingly, internet traffic generally, including podcast traffic, is conducted through IP addresses shared or recycled among multiple users, such as mobile network NATs (Network Address Translation) and corporate firewalls.  If two or 2,000 individuals per day download a podcast episode using the same device types and client software behind the same IP address, then the sample algorithm listed in the Version 2.0 guidelines count them all as a single listener.  This undercounts that podcast’s audience.  It’s why publishers have asked us to solve for accurately counting the number of users who download their podcasts in both single and shared IP environments. 

An important aspect of the Version 2.0 guidelines is providing a sample method for podcast analysis, while also encouraging and supporting discovery and innovation.  The Version 2.0 guidelines state generally that “companies are allowed to use more sophisticated mechanisms” than the specific methods listed in the guidelines. 

 The Solution

GIven the breadth of Podtrac’s measurement reach, Podtrac is uniquely positioned to:

  • Size the instance of multiple users downloading the same episode files in the same day using the same IP address

  • Develop and apply a more sophisticated method of analysis to our measurement system to avoid undercounting delivery.

Podtrac has developed proprietary algorithms to properly count listeners behind shared IP addresses. Podtrac uses a variable measurement window, including a 24-hour window and windows shorter than 24 hours.  The variable window was released as part of our algorithm updates on June 1, 2019.

The system is consistent with the Version 2.0 guidelines, which state: “No window is perfect, but shorter windows open up a risk of double counting requests and so should be done with care. Conversely, longer windows risk undercounting delivery via recycled mobile IPs and true multiple listens. Companies are allowed to use more sophisticated mechanisms…”

 Podtrac’s variable window is the best solution, yielding more accurate results. On average, the difference between a 24-hour window and Podtrac’s variable window is 6.5% across all shows.  After a rigorous review, the IAB Tech Lab and an independent auditor reviewed and accepted Podtrac’s variable analysis window as consistent with the V2 Guidelines.

 What this means to publishers and advertisers

Podtrac solves for the age-old question of identifying and separating downloads from the same individual and unique individuals behind shared IP addresses. This approach is consistent with the IAB Podcast Measurement Technical Guidelines Version 2.0, which encourage innovation with a provision for “more sophisticated mechanisms” which are increasingly important in a mobile world.  

Although a 24-hour window in the sample algorithm provided for in the Version 2.0 guidelines produces reasonable results and is useful to companies that aren’t in a position to develop more sophisticated systems, Podtrac’s variable window and analysis identifies audience members previously hidden behind shared IPs.    

Publishers and advertisers can be confident in the counts Podtrac provides.  The longest-running podcast measurement system -- currently measuring more than a billion downloads a month across tens of thousands of podcasts -- is now verified as compliant by the IAB Tech Lab.

Podtrac Measurement 2019 Update - What You Need to Know

Welcome to the new Podtrac Company blog. We’re launching this blog as a way to share what’s going on within Podtrac with podcasters who use Podtrac measurement.  

Podtrac is making an update to its measurement algorithm for calculating unique downloads which will go into effect on your Podtrac dashboard on June 1, 2019.  The new download numbers were reported for the first time for top publishers in the April Top 10 Publishers ranking.

While we’ve tweaked and adjusted the algorithms we use over the 14+ years we’ve been measuring podcasts, this update is more significant and we want to be as transparent as possible about why we’re making this change, when it will happen, and what you can expect.

Why is Podtrac making this change?

Podtrac is updating its measurement algorithm as part of the Interactive Advertising Bureau (IAB) Tech Lab compliance and certification process, as well as taking this opportunity to update for changes in the podcast landscape.  

Let’s take IAB compliance and certification first.  As you may be aware, the IAB formed a podcast working group back in 2014 to provide clarity in the marketplace by developing a common language around measurement.  80+ individuals from 40+ companies comprise the IAB Podcast Technical Working Group, and Podtrac was an integral part of the group, making significant contributions to both the Podcast Measurement Technical Guidelines version 1.0 and version 2.0.  The resulting Guidelines serve as a common set of principles or guidelines for podcast publishers and technology providers.

In September 2016, the IAB published its first Podcast Measurement Technical Guidelines (1.0).  There was no significant interest from IAB or its members to develop a compliance program when these standards were released.

In December 2017, the IAB published Podcast Measurement Technical Guidelines 2.0.  Shortly thereafter in early 2018, Podtrac implemented additional internal checks to audit website players and apps to ensure against the counting of podcast preloads, among other measurement implementation checks.  Later in 2018, the IAB made available and then launched the IAB Tech Lab Podcast Measurement Compliance Program as a new means to certify that interested companies adhered to specific interpretations of the 2.0 Guidelines.  For much of 2018, there wasn’t much interest from advertisers or publishers in the certification process, and there was a question if member companies of the technical working group would pay for and undergo certification. So far, only five of the 40+ member companies have completed the process.  

Increasingly, advertisers are getting behind the IAB Compliance Program as a way to make it easier and more reliable for them to make advertising decisions across multiple shows, publishers, hosting and ad insertion companies.  They now often request companies that submit advertising proposals to identify shows with IAB 2.0 certified counts. Based on this advertiser interest, Podtrac began to participate in the Compliance Program in late 2018. On a recent IAB Audio Committee call, it was announced that several other companies are in the process of being certified.

Podtrac is supportive of the IAB Guidelines and advocates for wide adoption of the Guidelines across the industry.  A shared understanding of podcast metrics is necessary to support the continued growth of podcasting and to give advertisers and investors the support they need to confidently expand investment in the industry.  

As for changes in the podcast landscape, while podcasting as an industry has changed and evolved, so has the way in which listeners access content (devices, streaming vs downloading), the platforms available to listen to podcasts (a plethora of apps beyond iTunes and Apple Podcasts with unique ways of providing data), the content publishers provide (length, publication frequency, etc), and just about every aspect of podcast distribution -- all with impacts on tracking metrics which filter down to the show level.  While we have always updated our analytics over time for these types of impacts, we are also taking advantage of this update to incorporate more wide-reaching adjustments.

How will the update affect my numbers?

The good news is that your unique monthly audience numbers (US and Global) will not see substantial change -- these are the “reach” numbers that Podtrac uses to determine our industry rankings so those rankings will not be affected.  

However, the not so happy news is you should expect to see your download numbers decrease to be consistent with the new guidelines.  Keep in mind that your download numbers might go up or down anyway based on any seasonality associated with your show or podcast consumption trends in general, but the overall impact from the new algorithm changes will be a more conservative download count per the IAB standard.

We understand this is difficult to hear, and while we wish it weren’t so, we do believe moving in the direction of an industry standard will benefit all publishers and the entire industry in the long run. You may have already seen or are beginning to see changes in your download numbers from hosting providers or other sources.   While metric adjustments are difficult for all involved, podcasting is a young industry and such a change is in line with what has happened in other industries such as display, radio and online video, and is necessary for growth.

How much will my download numbers decrease?

Not all podcasts will be affected to the same degree and it won’t be clear what the exact impacts are at a podcast or publisher level until mid to late July for new episodes which posted in June. Factors such as download behavior, episode length, bit rate, and hosting platform will determine the degree to which your shows’ download numbers are impacted.  Some shows will experience slight decreases while others more significant decreases. There is no way for us to tell any specific show the exact amount they will be affected by the updates until the updates are in place.

How will these changes impact ad delivery metrics?

Most larger podcast publishers and shows use dynamic ad insertion, with ad delivery metrics provided by those systems while using Podtrac data for audience sizing.  To date, most dynamic ad insertion companies for podcasts have not been IAB 2.0 Certified. So the industry is still at the beginning stage of these standards being implemented and certified for ad delivery.  Presumably some ad insertion companies will make changes to their systems, which will in turn change their numbers. Some have already implemented some changes and are in the process of becoming certified.

What if I am using Podtrac download numbers for ad sales and delivery?

Many podcast publishers regularly look at their Podtrac numbers to develop expected episode delivery counts for future episodes, and these frequently change, up or down.  If you use your Podtrac numbers this way, we recommend you do this analysis in mid to late July so you have 30 to 45 days of data to review for new episodes posting in June. Then with the June and July Podtrac numbers, consider changes up or down to your pricing based on what makes the most sense for your show.  Note that for direct response advertisers, the impact of the new counts for most shows will likely be minimal to the extent the ads are performing at the cost per episode they currently pay.

Wasn’t Podtrac already IAB 2.0 compliant?

Both versions of the IAB Guidelines are just that - guidelines - with room for interpretation in various areas of the guidelines and with areas of measurement that are not specifically addressed.  Podtrac has always been compliant with the guidelines and as mentioned earlier we were an integral member of the team that wrote them. However, with the advent of the IAB Certification program, we are beginning to see more coalescing around specific interpretations of the guidelines.  In our view this maturing of the industry and the standards makes this the right time to make adjustments to our algorithm.

Podtrac is proud to have served the podcast community with free metrics since 2005 and we look forward to continuing to support podcast industry growth.