Excel formula to find last non blank cell in a column starting on a certain row

Question

So I've got a column of data that I want to count the non blank cells after a certain row.

Here's an example of what I have:

So, in this example, I would like to start counting non blank cells in column A starting on row 13 (which would be a total of 4). If you look at the formula I have entered into cell D12 I can get the value I'm looking for with this formula:

=COUNTA(A:A)-11

I could use this formula:

=COUNTA(A13:A16)

but the point is the last cell with data in it can change due to entering different amounts of data in the column.

But I'm wondering if there is a different formula I could use that would count non blank cells from a certain row down regardless of the amount of data I enter into the column from a certain row down using an open ended range, kind of like this:

=COUNTA(A13:A)

This formula doesn't work but it kind of illustrates what I tried to do that didn't work.

Answer 1

from my comment above:

Well, you could always get the last used row dynamically and incorporate that, not sure what your benefit is over using the last row:

=COUNTA(A13:INDEX(A:A,LOOKUP(2,1/(A:A<>""),ROW(A:A))))

This makes it somewhat "open" ended I guess. Unfortunately it isn't GS =)