Glossary A–ZLetter F
Fill rate
Fill rate states what share of the advertising opportunities offered was actually filled with paid advertising.
It is given as a percentage. In programmatic trading it usually refers to the requests a seller sends to the market and how many of them find a buyer.
An example: on a given day a network offers 2,000 free slots in its loops through a sell-side platform, and 500 of them are bought. The fill rate is then 25 percent. The operator fills the remaining slots with house ads, directly sold campaigns or filler content. The metric shows how well a sales channel takes up what is on offer.
A high fill rate is not automatically good: it can also mean that slots were sold too cheaply. A low one can be due to a floor price that is too high, industry rules that are too narrow or the time of day. Fill rate is narrower than utilisation, which looks at the entire inventory across all sales channels. Operators should report both figures separately and always read them together with the price achieved.