Custom Dimension (GA4)
A custom dimension in GA4 is a user- or event-scoped property you define and send with events — extending the default dimension set with attributes specific to your business.
In context
Custom dimensions unlock segmentation that default GA4 cannot provide: page category, content author, customer tier, plan type, lifecycle stage. Implementation: define the dimension in GA4 admin (event-scoped or user-scoped), modify GTM (or your tagging code) to send the parameter on relevant events. Use sparingly — GA4 limits custom dimensions to 50 event-scoped and 25 user-scoped per property.
Toronto SEO's GA4 setup defines a 'content_cluster' event-scoped dimension on every pageview — letting reports break out organic performance by AI Search vs Glossary vs Playbooks vs Comparisons.
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