What is a bid response?

A bidder's reply to a bid request, stating the price it will pay and the creative it will show if it wins the impression.

How is a bid response evaluated?

The exchange compares all responses, applies the auction rules and any floor, selects the highest eligible bid, and serves that bidder's creative — within the request timeout.

What makes a bid response fail?

Arriving after the timeout, referencing non-compliant creative, or pricing the impression poorly so the bidder overpays or wins the wrong inventory.

Growth Marketing Glossary

Bid Response

bid re·sponse/bɪd ɹɪˈspɑns/noun

The bidder's answer — a price, a creative, and a promise to pay if it wins the impression.

Schematic — bidders return prices; the highest bid wins the impression

Term: Bid Response
Is: A bidder's reply with price + creative
Sent by: Demand-side platform / bidder
Evaluated under: Auction rules

Forms & parts of speech

bid response · noun

A bidder's price and creative.

"The exchange compares every bid response, applies the auction rules, and serves the winner's ad."

Definition in plain terms

A bid response is a demand-side bidder's reply to a BID REQUEST — the message stating the price it will pay for the impression and the creative (or creative reference) it wants to show if it wins. For each bid request an exchange broadcasts, it collects the bid responses that come back, evaluates them under the prevailing auction rules, and serves the winning bidder's ad — all in the milliseconds before the page renders.

The mechanics

A bid response contains the bid price, the creative markup or its reference, the buyer and campaign identifiers, and any deal or category metadata the exchange needs to validate it. The exchange compares all responses, applies the AUCTION rules (most exchanges run a variant of a second-price or first-price auction) and any floor, picks the highest eligible bid, and fires a win notice. A bidder that does not want the impression simply does not respond, or responds with no bid. Response speed matters as much as price — a bid that arrives after the timeout is discarded, so bidders balance how much computation they spend valuing an impression against the few milliseconds they have to answer.

When it matters

The bid response is where a buyer's strategy becomes a concrete commitment: the price encodes everything the bidder believes about the impression's worth, and the creative encodes what it will show. It matters most for bid pricing and pacing — bidding the true value of each impression rather than a flat rate — and for creative compliance, since a non-compliant creative in the response gets the bid rejected. The discipline is to value each impression on its merits, respond within the timeout, and make sure the creative referenced will actually serve, so won impressions are not wasted on rejected or broken ads.

Worked example. A bidder wins plenty of auctions but pays too much and shows mismatched creative. Tuning the bid response fixes both: the pricing model now sets each response from the impression's real value — viewability, context, audience fit — instead of a flat bid, and the creative reference is checked for compliance before the response is sent. The DSP wins fewer but better impressions at prices that match their worth, and far fewer wins are wasted on rejected creative — because the bid response, the moment where valuation and creative become a binding offer, is now built deliberately rather than by default.

Failure modes to watch. Bidding a flat rate instead of pricing each response on the impression's value; responding too slowly and missing the auction timeout; referencing non-compliant or broken creative that gets the bid rejected; and winning impressions the campaign cannot actually use well.

Synonyms & antonyms

Synonyms

bid responseOpenRTB bid responseRTB bid

Antonyms

bid requestno-bid response

Origin & history

The bid response is the counterpart object to the bid request in the IAB's OpenRTB protocol (RTB Project, 2010; IAB Tech Lab standard from January 2012). It standardizes how a bidder communicates price and creative back to the exchange, so any compliant demand-side platform can transact with any compliant exchange.

Etymology: source.

Usage trends

Search interest for this term over the last five years:

View interest-over-time on Google Trends →

Common questions

What is a bid response?: A bidder's reply to a bid request, stating the price it will pay and the creative it will show if it wins the impression.
How is a bid response evaluated?: The exchange compares all responses, applies the auction rules and any floor, selects the highest eligible bid, and serves that bidder's creative — within the request timeout.
What makes a bid response fail?: Arriving after the timeout, referencing non-compliant creative, or pricing the impression poorly so the bidder overpays or wins the wrong inventory.

Related tools & calculators

toolAuction win-rate calculator
toolBid-cap calculator

Resources & people to follow

referenceIAB Tech Lab — OpenRTB
referenceWikipedia — Real-time bidding
referenceRGM analysis — price every bid response on the impression's real value

Curated, non-competitor resources verified per term.

Related training

modulePerformance marketing

Disciplines

Areas of marketing where bid response is a core concern:

Performance marketingGrowth strategy

Sources

trendsGoogle Trends — "bid response"