How can I create a calculated field that uses the amount of filter items selected in Tableau?

Question

I am curious if there is a way to make a calculated field that uses the amount of items in a filtered selected. The calculation measure I am trying to do is:

2 x [Amount of Filter Items Selected]

For example, if I have 5 items selected like the filter attached below, it would be 2 x 5 and would therefore have a measure equal to 10 in my data source.

I am hoping to use this for a capacity dashboard that allows the user the select the dates they want, and then the total capacity auto calculates itself with this created measure. Thank you for any help!

Answer 1

If your filter is on a dimension [Current Dates], you can make a calculated field

[Capacity]:

2 * COUNTD([Current Dates])

This is view-dependent, and will only work as intended in a view with this filter. Otherwise, [Capacity] will be equal to double the number of distinct dates in your total set.