The GA4 Item scoped dimensions are used to capture detailed information about individual products or services within e-commerce events. 

There are two categories of GA4 item scoped dimensions:

#1 GA4 Built-in item scoped dimensions – These are ready-to-use dimensions available in the GA4 reporting interface or data API.

#2 GA4 custom item scoped dimensions – These are user-defined item-scoped dimensions.

GA4 Built-in item scoped dimensions

The following table provides a brief description of the various GA4 Built-in item scoped dimensions:

GA4 custom item scoped dimensions

The custom item scoped dimensions are user-defined dimensions.

If a built-in item scoped dimension does not capture any product-specific detail relevant to your business, create its corresponding custom item scoped dimension.

Following is an example to illustrate the point:

Let us suppose you sell handmade furniture. 

While the built-in “Item category” dimension might capture “Tables,” it wouldn’t tell you the specific type (coffee table, dining table, etc.).

You can create a custom item-scoped dimension named “furniture_type” to capture details like “Coffee Table” or “Dining Table” for each furniture item.

How to identify item-scoped dimensions in GA4?

Unlike session-scoped dimensions, which are prefixed with “session” (e.g., “session source/medium”), item-scoped dimensions do not have a specific prefix. 

Instead, they are identified by their inclusion within the items array in e-commerce events.

You may come across the following built-in item-scoped dimensions in your GA4 property:

You may assume that the built-in item-scoped dimensions that I listed use a prefix because they have ‘Item’ in their names, but they are not prefixes. It’s just the dimension name.

The entire name itself signifies the item-related nature of the data.

Item-scoped custom dimensions must be included within the items array of ecommerce events in GA4. 

This array serves as a container specifically for item-level data associated with the event.

Following is an example of how to include an item-scoped custom dimension in the items array:

Let’s assume you want to track a custom dimension called ‘product_color’ for each item in your e-commerce events. 

Here’s how you can do it in the context of a ‘purchase’ event using the data layer push method.

window.dataLayer = window.dataLayer || [];

window.dataLayer.push({

  event: ‘purchase’,

  ecommerce: {

    transaction_id: ‘T12345’,

    affiliation: ‘Online Store’,

    value: 59.99,

    currency: ‘USD’,

    tax: 5.00,

    shipping: 7.00,

    items: [

      {

        item_id: ‘P12345’,

        item_name: ‘Product 1’,

        item_category: ‘Category A’,

        item_variant: ‘Variant 1’,

        product_color: ‘Red’, // Custom dimension

        price: 29.99,

        quantity: 1

      },

      {

        item_id: ‘P67890’,

        item_name: ‘Product 2’,

        item_category: ‘Category B’,

        item_variant: ‘Variant 2’,

        product_color: ‘Blue’, // Custom dimension

        price: 30.00,

        quantity: 1

      }

    ]

  }

});

Here, the custom dimension ‘product_color’ is added to each item in the items array.

The Data Layer Push method ensures that the data is pushed to the data layer, which Google Tag Manager can then use to send the information to GA4.