Dimension

Definition

In web analytics, a dimension is a qualitative attribute that describes a characteristic of the collected data. Dimensions allow you to segment, filter and organize metrics in reports. For example, “Traffic source”, “Country”, “Device type” or “Page title” are dimensions.

Dimensions in GA4

GA4 offers predefined dimensions covering acquisition (source, medium, campaign), behavior (page title, event name), technology (browser, operating system), demographics (country, city) and time (date, hour).

GA4 also allows you to create custom dimensions based on event parameters or user properties. For example, an article_category parameter sent with the page_view event can become a usable dimension in reports.

Dimensions vs metrics

The distinction is fundamental. A dimension answers “what” or “who” (which channel, which page, which country), while a metric answers “how many” (number of sessions, conversion rate). In a report, dimensions form the table rows and metrics form the columns.

Limits and best practices

GA4 limits you to 50 event-scoped custom dimensions and 25 user-scoped custom dimensions. Plan your dimensions ahead during the GA4 setup to avoid hitting these limits. Poorly named or redundant dimensions complicate analysis and clutter the interface.