onceusers

Onceusers is a term used in web analytics to describe visitors who interact with a site or app only once within a specified time window, such as 30 days. It is used to differentiate single-visit engagement from recurring or returning engagement. The term is not standardized across platforms and may be defined differently by analytics providers.

Originating as a shorthand for one-time users, onceusers reflects a focus on session-based counting rather than user-level persistence. In practice, definitions vary in terms of what constitutes a visit, how cookies or device IDs are handled, and whether returning visitors who clear data are counted as new.

Onceusers are identified by unique identifiers tied to devices or cookies. Accurate counting requires persistent identifiers and consistent sessionization rules; privacy controls, ad blockers, cross-device usage, and cookie deletion can cause misclassification.

Analysts may use onceusers to estimate reach or to contrast with returning users for retention analysis, conversion attribution, or frequency capping. The metric can illuminate audience breadth but may overstate reach if single devices host multiple users or multiple visits are partially counted as single visits.

Related concepts include unique visitors, first-time visitors, and returning visitors. Some sources use one-time visitors or single-visit users as synonyms or as a distinct subset within a broader user taxonomy. Because definitions depend on data collection policies, cross-device tracking, and privacy settings, onceuser counts are sensitive to methodology and may be unreliable for longitudinal analyses.

See also: unique visitors, returning visitors, session, user engagement.