Hi Sean
I may be wrong but I don't think that you can just sum visible cells with a native excel formula.
However, if you need to do it, one alternative is to use an UDF and use it like a formula, like
=sumvisible(D3:D19)
I did an example, just paste the code in a regular module.
Hope this helps
PGC
Code:
Option Explicit
Function SumVisible(rR As Range) As Double
Dim rC As Range, dtotal As Double
For Each rC In rR
If Not rC.EntireRow.Hidden And Not rC.EntireColumn.Hidden Then dtotal = dtotal + rC
Next
SumVisible = dtotal
End Function