Video by: Reid Havens
If you've ever written a running total in DAX, you know it's more work than it has any right to be. CALCULATE, FILTER, a column reference you have to get exactly right, and a quiet prayer that it behaves at the subtotal level. Visual calculations let you write RUNNINGSUM([Sales]) and get on with your day.
They're a calculation layer that lives inside the visual itself, working on the data that's already been aggregated rather than querying the whole model. That's also why they're often faster, sometimes dramatically so on DirectQuery.
I walk through the core functions (running totals, moving averages, PREVIOUS and NEXT for period comparisons, FIRST, LAST, INDEX, and RANK), then the hierarchy functions like COLLAPSE and EXPAND that make "% of parent" and "% of grand total" almost trivial. We also get into AXIS and RESET, which control the direction a calculation runs and where it restarts, because that's the part that quietly breaks people's running totals across years.
One honest caveat. Yes, they're easier and faster. But because each one only lives in a single visual, they can fragment your business logic across reports if you're not careful, so I cover when a visual calc is the right call and when it really should be a centralized measure.
