Coverage (ad coverage)

Coverage answers a simple question: when my page asked for ads, how often did it get any? If a page sends 1,000 ad requests and 850 come back with at least one ad, coverage is 85%. Display advertising calls the same idea fill rate.

Coverage depends mainly on advertiser demand. A keyword with many bidders in a wealthy country will nearly always return ads. An obscure term, a small language or a country with few advertisers may return nothing. Safe-ads filters, restricted topics and quality problems with the publisher's traffic can also reduce it.

It matters because an empty results page earns nothing. The visitor was paid for, clicked a keyword, and found no ads. Low coverage therefore drags down RPV even when the clicks that do happen pay well.

Buyers watch coverage by keyword and by country. A sudden drop across the board can be an early warning that the feed has restricted the account. It also explains why the Google feed is valued: a bigger advertiser pool usually means higher coverage than smaller feeds manage on the same terms.

An example

For example, 2,000 requests at 60% coverage produce 1,200 pages with ads. At 90% coverage the same traffic produces 1,800, a 50% increase in earning opportunities at no extra traffic cost.