A transaction, for conversion purposes, is a completed purchase counted against the population of visitors who had the opportunity to make it 12. In a physical store, conversion rate is the number of people who buy from the store out of the total number of people who entered, calculated as transactions divided by traffic and multiplied by 100 to give a percentage 1. Conversion rate in retail is described as the percentage of visitors to a physical store who make a purchase 2. Another definition frames conversion rate in terms of traffic and the number of sales transactions, with store traffic defined as the number of walk-ins 3.
Online and omnichannel counting
Online, the counted unit is a session in which an order was completed, with overall session conversion rate defined as the total number of sessions with order completed divided by the total number of sessions 4. The IAB/MRC Retail Media Measurement Guidelines state that an omni conversion rate must be based on orders per impression or units per event, and that a units-per-event basis requires the retailer to give transparency on the methodology and how it is differentiated 5. Conversion volume similarly focuses on orders per visit, or units per event 6. Units per transaction is a separate metric tracking the number of items sold in a transaction, so a unit count and a transaction count are not interchangeable 7.
Advertising and audience contexts
In advertising measurement, a conversion is an action taken as a result of an advertising exposure that aligns with the campaign goal, and crediting it implies attribution to one or more ad exposures 8. Used as an audience characteristic, first-time purchases may be distinguished from repeat purchases, with repeat purchases excluded from the converted audience count 8. That conversion can be online or in-store where some form of user tracking, such as a loyalty card, is in place 9.