Report bucket fields versus formula fields
Key Takeaway
A bucket column groups a field's existing values into named categories, but it exists only in the report where you create it. Reuse across many reports is the main reason to choose a formula field on the object over a bucket column.
A bucket column (also called a bucket field) sorts report records into categories you define, such as Small, Medium and Large, inside one report. A formula field, by contrast, is created on the object. A row-level formula calculates a new value for each record inside a report. The right choice depends on two questions: must the grouping be reused across reports, and do you need to group values or calculate them?
What a bucket column does
A bucket column lets you categorize report records quickly, without creating a formula or a custom field. You create one by choosing a field from the report type and then defining several buckets that group its values. You can sort, filter and group by a bucket column, just like any other report column.
For example, imagine a report on accounts with a bucket column named Size, based on # Employees. It could group accounts into three buckets: Small (5,000 or less), Medium (5,000 to 10,000) and Large (more than 10,000). If an account grows or shrinks, it switches buckets automatically, so the categories stay current without any data changes.
You can bucket three data types: numeric, picklist and text.