Sell Through Rate is a sell side metric which is sourced and calculated from either an Ad Network’s Ad server or a individual publisher ad server and represented as a percentage. It represents the number of paid impressions sold divided by the number of ad impressions available for sale.
The Sell Through Rate formula is represented by;
(Paid impressions / Total impressions served) x 100 = Sell Through Rate %
Your website had 1,000,000 total impressions or “ad calls” for a given period. Only 870,000 of those impressions returned a paid advertisement:
(870,000 / 1,000,000 ) x 100 = 87% Sell Through Rate
The Sell Through Rate is a culmination of all digital sales options which represents “paid impressions”: such as
Header Bidding / Prebid
Programmatic Open Exchange
CPA / Cost Per Acquisition / Affiliate
CPC / Cost Per Click
Price Floor, network errors, internet congestion, sales cycles, timeouts and users leaving a web page before the ad is delivered to the page all contribute to why a perfect 100% sell through rate rarely happens.