Auction timeout

Every programmatic auction has a clock. The seller decides how long to wait for bidders to reply, and once time is up, it picks a winner from the bids that arrived. In OpenRTB, the "tmax" field in the bid request tells bidders their deadline in milliseconds. In header bidding wrappers such as Prebid, publishers set a bidder timeout for the in-page auction.

Timeouts are a trade-off. Short timeouts keep pages fast and limit latency, but more bidders time out and revenue may fall. Long timeouts collect more bids but slow the page and can hurt viewability and user experience. Server-to-server RTB deadlines are typically a few hundred milliseconds or less; client-side header bidding timeouts are usually longer because they include network round trips from the user's device.

Publishers monitor timeout rates by bidder and drop or throttle partners that are consistently late. Buyers keep their bidders and fraud checks fast enough to answer in time.

Think of it like this

An auction timeout is like the moment an auctioneer bangs the gavel: raise your paddle one second later and it does not count.

An example

A publisher sets a 1,000 ms Prebid timeout. One SSP answers in 1,150 ms on 20% of auctions, so those bids are discarded; the publisher moves that SSP to its server-side setup.