Fill Rate

Fill Rate measures what fraction of available inventory actually gets monetized. A podcast feed that generates 1,000,000 ad requests per week and fills 800,000 of them has an 80 percent fill rate. The remaining 20 percent is either left silent, replaced with house promos, or filled with PSAs: all of which yield zero revenue.

Fill rate is a function of demand, pricing, and inventory quality. A publisher with a high floor price and strong demand can run at 95+ percent fill; a publisher whose floor is too high or whose audience is niche may struggle below 60 percent. Programmatic platforms rely on SSP integrations and real-time bidding to lift fill rates, but the fundamental economics are always shaped by whether buyers want the inventory on offer.