The affiliate glossary ↗AFFDude / Field notes
Fill rate
In plain English
What does Fill rate mean?
The share of ad requests a network actually fills with an ad. Low fill means unsold inventory for the publisher.
Publishers care about fill rate because unfilled requests earn nothing; they stack networks in a waterfall to raise it. For media buyers it hints at competition: a network with low fill in your GEO may sell you cheap, plentiful inventory.