Header Bidding Timeout Calculator
Pick the right Prebid timeout for your site. Enter your bidders and their typical response times, and this free header bidding timeout calculator shows how many bids arrive in time, how long ads are delayed and which timeout gives you about 90% of bids without slowing the page.
Your bidders
Enter each bidder’s typical (median) response time. You can find it in your Prebid analytics or with a header bidding Chrome extension.
Auction settings
Expected bid participation
Each bidder’s chance of answering in time is estimated from its median response time with a typical spread (90% of responses within about 1.8 × the median). Mobile adds about 35% latency. Real results vary, so test changes on your own traffic.
Timeout vs bid participation
How to use the calculator
- List your bidders and enter each one’s median response time in milliseconds.
- Choose Desktop or Mobile.
- Move the timeout slider to your current setting.
- Check the expected bid participation, missed bids and longest ad delay.
- Read the suggestion and the chart to find the sweet spot for your bidders.
What the header bidding timeout does
In header bidding, the page asks several ad exchanges for a bid at the same time. The timeout is how long the page waits for answers before it sends the bids to the ad server. Bids that arrive later are dropped. In Prebid.js the setting is called bidderTimeout.
It is a trade-off. A short timeout shows ads quickly but loses slower bidders. A long timeout collects more bids but delays every ad, and some visitors scroll past before the ad appears. Learn how the auction works in our Prebid.js setup guide.
How the calculator works
Response times are not fixed. A bidder with a median of 500 ms sometimes answers in 300 ms and sometimes in 900 ms. The calculator models each bidder’s response times with a typical spread, where 90% of answers arrive within about 1.8 times the median. From that it calculates the chance that each bidder answers before your timeout.
- Expected bid participation is the average chance across all bidders.
- Missed bids per 1,000 auctions shows how many bids are lost to the timeout.
- Longest ad delay adds the delay before the auction starts, the slowest bid you wait for and the ad server call.
- Suggested timeout is the shortest timeout at which about 90% of bids arrive.
Typical timeout settings
| Setup | Common timeout | Notes |
|---|---|---|
| Desktop, 3–6 client-side bidders | 1,000 – 1,500 ms | A good starting point for most sites |
| Mobile web | 1,200 – 2,000 ms | Slower networks need more time |
| Many bidders (8+) | 1,500 – 2,000 ms | Consider moving slow bidders server-side |
| Prebid Server | 500 – 1,000 ms | Server-to-server calls are faster |
| Prebid.js default | 3,000 ms | Usually too long for display ads |
These are common ranges, not rules. Always test a new timeout on part of your traffic and compare page RPM before and after.
How to reduce header bidding latency
- Remove bidders that rarely win. A bidder that wins less than 1% of auctions mostly adds delay.
- Move slow bidders to Prebid Server. See server-side header bidding explained.
- Load Prebid early. Start the auction as soon as possible and don’t wait for other scripts.
- Lazy load ads below the fold. Run auctions only for slots that will be seen.
- Watch Core Web Vitals. Read Core Web Vitals and ads to keep the page fast.
- Check your setup in the browser. Our list of header bidding Chrome extensions shows bid times live.
New to header bidding? Start with AdSense vs header bidding. To estimate what more bids could earn, use the ad revenue calculator and see all our free tools.
Frequently asked questions
What is a good Prebid timeout?
Most publishers land between 1,000 and 1,500 ms on desktop and a little higher on mobile. The best value depends on your bidders: it should be long enough for most bids to arrive, but no longer, because every extra millisecond delays your ads.
What is the default timeout in Prebid.js?
Prebid.js uses a default bidder timeout of 3,000 ms if you don’t set one. That is usually too long for display ads, so most setups change it with pbjs.setConfig({ bidderTimeout: … }).
What happens when a bidder misses the timeout?
Its bid is ignored for that auction, even if it would have been the highest. The ad server then picks a winner from the bids that did arrive.
Does a longer timeout always mean more revenue?
No. After a point you gain very few extra bids, while ads appear later. Visitors who scroll past the slot never see the ad, so viewability and revenue can drop.
Why is the mobile setting slower?
Mobile networks and phones add latency. The calculator adds about 35% to each bidder’s response time when you choose Mobile, which is a typical difference. Use your own analytics data for exact numbers.
Where can I find my bidders’ response times?
Prebid analytics adapters, your SSP dashboards and header bidding Chrome extensions all show bid response times. Use the median, the time within which half of the responses arrive.