New-to-brand is a defined Amazon advertising measure. It should be read with its history window and reporting scope beside it.
Use the actual definition
Amazon’s new-to-brand sales definition uses the previous 365 days of purchase history with the brand. It does not mean the customer has never purchased from the brand. Amazon’s current performance metric definitions.
Confirm that the measure is available for the ad product and report you are using. Record the marketplace, dates and attribution scope.
Keep the numerator clear
Retain the metric’s exact label: customers, orders or sales are different units. Keep the new-to-brand subset alongside the total from the same report. Do not mix customer counts with order counts when calculating a share.
If calculating spend per reported new-to-brand order, label it with that unit and scope. It is not a complete account of acquiring a customer across every channel.
Record what remains unknown
The report does not establish every purchase made outside its history and reporting scope. Keep direct-to-consumer records separate unless there is a permitted, well-defined basis for comparison.
Write the next question before changing spend: the audience reached, creative message, product availability or repeat purchase evidence. Read each question with the source that can answer it, and leave the unresolved parts explicit.