What are table calculations in Tableau?

A table calculation is a calculation applied to the values already in a Tableau view, after the underlying query has returned and aggregated the data — as opposed to a regular calculated field, which is computed as part of the query itself.

• Common examples include running total, percent of total, rank, moving average, and difference from previous value.
• Table calculations depend on the structure of the view — specifically the partitioning (which fields reset the calculation) and addressing (which fields the calculation runs across), both configurable via "Compute Using."

Quick Table Calculation -> Running Total
-> Compute Using: Table (down)
-> produces a cumulative sum as you move down rows

Because they operate on the already-aggregated view rather than the raw rows, table calculations are the tool of choice for anything inherently relative to other rows in the result — a rank, a running total, or a percent-of-total simply can't be computed correctly by looking at one row in isolation, which is exactly the situation a normal row-level calculated field is built for.