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Adding a Custom Dimension Using a Looker Expression

Most fields in the Field Picker are created by your Looker developers. If your Looker admin has enabled the custom fields feature and given you access, you can add new custom dimensions and measures yourself. Unlike table calculations, a new custom field becomes a new Field Picker choice on that Explore for certain users.

Quick Guide

You can create a new custom dimension using a Looker Expression and one or more other dimensions:

  1. Expand the Custom Filters section.
  2. Click New.
  3. Choose Custom Dimension.
  4. Specify the name and format that you want to use. In the main box, type a Looker Expression that calculates the value for your dimension. The editor will help suggest field names and give syntax help for any functions you use. For more details on using this editor, see the Creating Looker Expressions page. You can use any Looker functions and operators that can be used in other custom filters.
  5. Click Save. The Field Picker displays your new custom dimension in the Custom Fields section. Like other dimensions, you can click a custom dimension’s name to display it in a query. You also can click its Filter button to use it as a filter in a query.

Viewing and Using Custom Fields

If you are allowed to create custom fields, then you can see and edit any custom fields in the Custom Fields section of the Field Picker. If another user creates a custom field and passes you the Explore’s URL, then you can see that custom field in the Field Picker. The URL must include the qid parameter (such as

You can interact with these custom fields as you would with any other measure or dimension, including filtering on them or adding them to visualizations. (If you create a custom dimension then you can also pivot on that field.) Only users who are allowed to create custom fields can add a custom field to a query in an Explore, Look, or dashboard tile.

If a user cannot create custom fields, then the Field Picker does not display the Custom Fields section and the user cannot add a custom field to a query. However, users do not need any special permissions to see a custom field used in a shared query, Look, or dashboard. Also, users can click Explore from here on a Look or dashboard tile to create a new query using that field. Good naming of fields is important because these users cannot see the definition of a custom field.

Additional Ways to Add Fields

There are several ways to add new fields to your Explore:

Under Construction: We’re working on adding more to this page. In the meantime, check out the Adding a Custom Measure from a Dimension page. That page includes general information about custom fields.