A rollup field performs calculations, create aggregates, and build formulas on specific cells from records that are linked to another field in your table.

Add the rollup field

To add a rollup field, click the plus sign located to the right of your existing fields. Then, select "Rollup" from the list of available field types. 

Choose a table to summarize records

After adding the rollup field, the first option you can configure is to choose which table you want to use to summarize records. In the example below, the only other table in the base, "Design projects", is automatically selected. 

Choose a field to rollup

Next, choose a field that you want to rollup; this field will be used to bring in information from the other table you've linked to into the table where the rollup field is being created. Below, a date field is selected from the linked table. 

Limiting which records are used

After choosing the field that you want to rollup, the next option below it is to only include linked records that meet certain conditions. This option allows you to only rollup records according to the conditions, or criteria, that you set. For example, you may only want to rollup records that have a value over a certain amount, or in the example below, records that are not complete and have a kickoff date that falls after the first of the year 2020.

When these conditions are added, only records that match these conditions will be used to produce a value in the rollup field. 

Insert a rollup function

The last step is to select a way to aggregate the field values from the linked records. When you start editing the aggregation input, you will see suggestions for potential rollup functions with a brief description of each function.

As an example, you can rollup the date field and display the most recent date listed using the MAX(values) function.

After you've finished configuring the rollup field settings, save the field. You'll now see any values that can be rolled up from the linked table.

Troubleshooting

If your table has a field with the name "Values" and you create a new Rollup field you will run into some unintended behavior. Under the hood, when you create a new Rollup field that field is essentially attempting to create a new field to aggregate data that will be named "values"(this is shown in the formula above with the syntax MAX(values)).  However,  if a field with the name "values" already exists, the Rollup field will use that existing field instead of creating a new one. You can avoid this behavior by changing your field name to anything other than "values" (i.e. "value" works)!