Glossary
What is Floor price?
Also called: price floor, reserve price
A floor price is the lowest CPM a publisher will accept for an impression. Bids below the floor are rejected.
हिंदी में पढ़ेंA floor price, also called a price floor or reserve price, sets the minimum a bid must meet. Floors can be set in the ad server, in each SSP and in Prebid’s Price Floors module, and are usually passed to buyers in the bid request, for example as imp.bidfloor. Not every floor is shown to buyers, though.
Floors can help or hurt. Say a buyer values your slot at $3.00 but expects little competition, so it plans to bid $1.60. A $2.00 floor makes it bid at least $2.00, and you earn $0.40 more CPM. Raise the floor to $3.50 and that buyer drops out; if nobody else clears it, the impression goes unsold or to a house ad.
Revenue is CPM multiplied by filled impressions. A higher CPM on fewer impressions can mean less money. After any floor change, compare revenue and fill rate, not CPM alone, and change one floor at a time.
Example
100,000 impressions sell at a $1.80 average CPM, earning $180. A new floor lifts the CPM to $2.20 but only 70,000 impressions sell, so revenue falls to 70,000 × $2.20 ÷ 1,000 = $154.
Why it matters to publishers
In first-price auctions the floor is one of the main levers a publisher has over price, alongside competition, so it should be set from data.