Glossary
What is Price granularity?
Also called: granularity, price buckets setting
Price granularity is the size of the price steps Prebid uses when it rounds bids down into price buckets for the ad server.
हिंदी में पढ़ेंGoogle Ad Manager line items match exact key-values, so the ad server cannot read every possible bid. Prebid rounds each bid down into a price bucket and sends it as hb_pb. Price granularity sets the size of those steps.
Prebid has five built-in options. Low uses $0.50 steps up to $5. Medium, the default, uses $0.10 steps up to $20. High uses $0.01 steps up to $20. Auto and dense are sliding scales, with finer steps at lower prices. You can also define custom buckets, fine where your bids cluster and coarser elsewhere, with the cap near your 95th-percentile bid.
Rounding does not change what a winning bid pays; it changes how the bid competes in the ad server. Coarse steps can make a bid lose to other demand it actually beat, while fine steps need more line items. Whatever you choose, your line items must match it exactly.
Example
A $2.87 bid enters Ad Manager as 2.80 with medium granularity, or 2.50 with low. If AdX bids $2.60, the low-granularity bid loses at 2.50, even though $2.87 would have won.
Why it matters to publishers
The wrong granularity quietly loses auctions you should win. Checking that it matches your line items exactly is one of the simplest Prebid audits.