A custom metric is a numeric value you define and send with events so that reports can add it up or average it. In GA4 you send it as an event parameter and register it under custom definitions, choosing a unit such as standard, currency, distance or time. Where a custom dimension describes something, a custom metric counts or measures it.
When a custom metric helps
Use a custom metric when the value is a quantity you want totaled or averaged across many events. If you only need to filter or group by a value, a custom dimension is usually the right choice.
- Seats selected in a pricing calculator
- Estimated contract value on a quote request
- Seconds of a product video watched
- Number of results returned by site search
Calculated metrics
GA4 also supports calculated metrics, which combine existing metrics with a formula, for example key events per engaged session. They save you from exporting data to a spreadsheet for common ratios. Availability and limits differ between standard and 360 properties.
Units and data hygiene
Send numbers as numbers, not strings, and pick the unit carefully when registering, because the unit controls how values are displayed. Currency metrics in particular should be consistent in currency, or every total will be wrong.
Example
Valuing calculator use
Imagine Slatehaven, a backup service, sends a seats parameter when someone finishes its pricing calculator, registered as a standard custom metric. The team can see total seats modeled by channel and spot that organic visitors model larger teams than paid visitors, which informs where to put enterprise content.
Common mistakes
Sending values as text
A value like '12 seats' cannot be summed. Send 12.
Creating a metric for something already built in
Check GA4's built-in metrics and recommended event parameters, such as value and currency, before inventing your own.
Questions
Dimensions are attributes you group by, such as plan tier. Metrics are numbers you add or average, such as seats.
