How to determine the last Row used in VBA including blank spaces in between [duplicate]

Answer 1

The Problem is the "as string" in your function. Replace it with "as double" or "as long" to make it work. This way it even works if the last row is bigger than the "large number" proposed in the accepted answer.

So this should work

Function ultimaFilaBlanco(col As double) As Long        
    Dim lastRow As Long
    With ActiveSheet
        lastRow = ActiveSheet.Cells(ActiveSheet.Rows.Count, col).End(xlUp).row
    End With            
    ultimaFilaBlanco = lastRow          
End Function