Why is there a low ad inventory being filled on my podcasts?

There are a few factors that can influence the number of ads served in your episodes, even when ad inventory is available.
​W​e work with a wide network of advertisers and actively ​d​eliver ads that are most relevant to your audience. However, ad delivery depends on several dynamic factors​, such as listener location, content category, demographics, and listener behavior. If these factors don't align with a campaign’s specific targeting criteria, some ad slots may remain unfilled.

In other words, while your episodes may include multiple available ad slots (inventory), only a portion may be filled if the targeting requirements aren’t fully matched at that moment. This doesn’t reflect a lack of advertiser demand​ but rather the system’s effort to serve the most relevant and high-quality ads to your listeners.
To improve ad fill rates, consider growing your reach in high-demand regions and regularly publishing new content to keep your podcast active and attractive to more campaigns.