+OFFSET and COUNTA in VBA

Hi Baphony
First comment : avoid using .Activate and .Select as it slows down your code. Most of the time you don't need to use it.

Here's an example, if I understood well :

Sub supplierdefine1()
   Dim rng As Range
   With Sheets("VendorsInCosts")
      Set rng = .Range("A1:A" & .Range("A65535").End(xlUp).Row + 1)
      ActiveWorkbook.Names.Add Name:="suppliercostslist", RefersTo:=rng
   End With
   
   'Example :
   Dim rg As Range
   Set rg = Sheets("Vendor").Range("A2").Resize(WorksheetFunction.CountA(Sheets("PartsList").Columns("A:A")), 11)
' Just to verify the ranges address in the Execution pane
   Debug.Print rg.Address
   Debug.Print rng.Address
   
End Sub