Using Multiple Summarize Values in Calculated Field Calculations

I created a pivot table and it contains a cost field from my dataset. I dropped that into the Values area twice.
I summarized one as MIN and the other as MAX.
Now I want to use these two fields to create a Calculated Field but they don't show up as options to select.
How do I do this if they don't show up?
The MIN and MAX fields will change based on what Filters I apply to the pivot table and I need the MIN MAX to change accordingly.
Not something I can build into the dataset or know upfront for a Measure if using Power Pivot (which I am not).


Thank you!