Depending on what you want...
For last displayed value
==========================
LastUsedRow = ActiveSheet.Cells.Find(What:="*", SearchOrder:=xlRows, _
SearchDirection:=xlPrevious, LookIn:=xlValues).Row
LastUsedCol = ActiveSheet.Cells.Find(What:="*", SearchOrder:=xlByColumns, _
SearchDirection:=xlPrevious, LookIn:=xlValues).Column
For last value or formula
===============================
LastUsedRow = ActiveSheet.Cells.Find(What:="*", SearchOrder:=xlRows, _
SearchDirection:=xlPrevious, LookIn:=xlFormulas).Row
LastUsedCol = ActiveSheet.Cells.Find(What:="*", SearchOrder:=xlByColumns, _
SearchDirection:=xlPrevious, LookIn:=xlFormulas).Column
That "last value or formula" one will find the last cell with an actual
value or with a formula in it even if the formula evaluates to the empty
string ("").