Custom Metric (GA4)

A custom metric in Google Analytics 4 (GA4) lets a property report numerical values collected through custom event parameters. Custom metrics are event-scoped: a business might send a numeric estimate amount or quantity alongside a properly implemented event, then register the parameter as a custom metric in the property's Custom definitions settings. Simply sending a parameter does not automatically make it available as a custom metric in standard reporting. After registration, reporting can take 24–48 hours to become available, and property quotas apply. GA4 custom dimensions are generally used for descriptive attributes, while custom metrics use numeric values; calculated metrics combine existing metrics through a formula. A numeric business estimate is still a tracked value, not proof that a customer paid that amount. Use existing predefined GA4 metrics when they already meet the need, and test the underlying event and parameter before relying on custom reports.