For more than twenty years, CPM – Cost per Mille impressions has been the universal benchmark of digital advertising.
Born in the 1990s as the online adaptation of metrics already used in print and television, it gave a price to attention and standardized media planning, fueling the exponential growth of the digital ad market. Its strength was its simplicity: every thousand times an ad was shown, advertisers paid a fixed rate.
Today, however, the context has changed: fragmented audiences, increasingly diverse formats, and attention as a scarce resource.
In this scenario, a new set of metrics focused on people has become essential. This metric is referred to in different ways: CPUm (Cost per Mille Users), CPM reach in Nielsen’s manuals, or CPM-U (Cost per Mille Users) in currencies such as AGF in Germany. We adopt the CPM-U definition, as it is the most widely used and standardized at the international level. The shift from CPM to CPM-U marks a fundamental evolution: the value is no longer measured by the number of impressions served, but by the cost of reaching 1,000 users. A change in perspective that provides brands and publishers with a clearer and more transparent way of assessing campaign value.

WHY CPM IS LIMITED
CPM counts how many times an ad is displayed, but it fails to reflect what has now become the real currency of media: attention. The market is increasingly moving towards KPIs linked to attentiveness, the ability to capture and hold people’s focus. In this context, limiting evaluation to how many times an ad has been served does not reflect the real value of a campaign. Over time, this approach has revealed its weaknesses, especially in contexts where the quality of the relationship with the audience is what really matters: sponsorship projects, podcasts, spoken content, or immersive audio and video formats.

FROM COUNTING IMPRESSIONS TO USER-CENTERED VALUE
CPM-U addresses this gap. It no longer measures only how many times an ad is served, but how many users are actually reached by a piece of content. It is not a calculation of “unique users,” but rather a shift of focus: the reference point is no longer the machine delivering the ad, but the person exposed to it. This semantic and operational change opens the way to a more realistic evaluation of campaign value, because it associates cost with what brands and publishers truly care about: people.

AUDIO AND SPONSORSHIP: THE IDEAL GROUND
In several international markets – from the United States to Northern Europe – this approach is gaining traction especially in sponsorships, podcasts, spoken content, and native digital news formats. Here, the value for advertisers is not the number of impressions, but the cost of accessing a cluster of users, even if not exclusively unique. In these scenarios, CPM-U proves to be the ideal metric to capture and monetize community value.

WHERE IT IS ALREADY USED
CPM-U is not a theoretical invention; it already finds practical application across media. In television and video, for example, Germany’s AGF uses CPM-U as an official trading currency, calculating the cost for 1,000 people in the target. In radio and linear audio, Nielsen applies “CPM reach” as a proxy for cost per thousand listeners. Social platforms such as Meta have also introduced similar metrics, explicitly referring to the “cost per 1,000 accounts reached” in their reporting tools.
In digital audio and podcasts the adoption is even more evident. Networks such as Spotify, Acast, Wondery, or Podigee already price their inventory and sponsorships based on the cost per thousand validated listeners or downloads, following IAB standards. Spoken content follows the same logic, where the goal is to value not the impressions, but the users effectively reached and engaged. Branded content and newsletters are also moving in this direction: more and more creators and publishers are offering packages calculated on the cost per 1,000 subscribers or readers reached. Finally, in programmatic and data markets, offers based on CPM-U for targeted user segments are becoming increasingly common, standing apart from the traditional CPM for impressions served.
These examples show that CPM-U is already a consolidated reality across different industries, even though it has not yet been formalized as a global standard by the IAB.

CPM-U AS A BRIDGE TO ATTENTION-BASED METRICS
In recent years, advertisers and agencies have been demanding metrics tied to attention: time spent, engagement, ad recall. CPM-U does not measure attentiveness directly, but it shifts the focus back to the user. It acts as a bridge toward more sophisticated measurements, while maintaining the clarity and simplicity of a cost parameter that is easy to understand and communicate.

WHY A PARADIGM SHIFT IS NEEDED
The risk in today’s market is inflating numbers without delivering real value: impressions that generate no attention, metrics that confuse rather than clarify. CPM-U offers a way out: it does not replace CPM, but complements it, introducing a user-first parameter that allows the value of an audience to be expressed more clearly.

 AUDIOBOOST’S VISION
At Audioboost, we believe CPM-U is the right metric for a market phase in which digital audio and AI are reshaping the relationship between publishers, users, and brands. With proprietary solutions such as SpeakUp-Article™, Storycast, and AI Audio Lab, we can accurately measure the real impact on our users and translate it into value for advertisers and publishers. Audio is by nature a personal medium, capable of building a direct relationship with the listener.
Talking only about impressions in this context is reductive: what matters is the number of users who choose to spend their time and attention on a piece of content. With CPM-U, that value becomes tangible and measurable.

CONCLUSION
CPM has defined an era and remains a useful metric to understand the digital advertising market. But today brands, agencies, and publishers need to go beyond inflated impression counts and focus on people. This is where CPM-U – Cost per Mille Users comes into play, as a metric that reflects real value: simple to understand, transparent to communicate, and solid enough to build more sustainable business models. For Audioboost, this is not just a technical opportunity but a genuine paradigm shift. Digital audio, amplified by AI, is the ideal ground to establish CPM-U as the new currency between publishers and advertisers. It is no longer about how many times a piece of content is served, but about how many people choose to listen and dedicate attention to it. This is where the future of advertising is played out: less focused on impressions, more committed to creating authentic relationships with communities.