Parameters

Formatting

Use value_format_name parameter whenever possible. It lets Looker handle all the formatting of the output value of the field.

https://docs.looker.com/reference/field-params/value_format_name

Use value_format if you want to apply your own formatting to the field. You need to use Excel-style guidelines for formatting.

https://docs.looker.com/reference/field-params/value_format