<b>The hidden economics of the header bidding timeout</b>

<b>The hidden economics of the header bidding timeout</b>

Header bidding lets a publisher solicit bids from many demand sources in the browser <i>before</i> calling the ad server, so exchanges compete simultaneously instead of in a waterfall. The single most consequential setting is the timeout — how long the page waits for bids.

1. A short timeout (say 500ms) protects page speed but cuts off slower bidders, including some that would have bid highest. The publisher trades yield for latency.
2. A long timeout (1500ms+) captures more bids and lifts revenue per impression, but worsens Core Web Vitals and can reduce sessions, shrinking total impressions.
3. The optimum is not a number — it is the point where marginal revenue from one more bidder equals the marginal revenue lost to slower pages.

For buyers, the timeout is a silent filter on which auctions you even reach. If your DSP's bidder consistently responds in 600ms and a publisher runs a 500ms timeout, you are structurally excluded from that supply regardless of how much you would have paid.

<b>Why it matters:</b> when you can't win a known publisher at any price, measure your bidder's response latency against their timeout before assuming it's a deal or targeting issue. Latency is a competitive variable, not just an engineering one.