Here is my full code:

' (Declarations)

Dim cell_count As Long
Dim add_amount As Long
Dim cell_range As Range


Private Sub cell_setup()

cell_count = WorksheetFunction.CountA(Range("A8:A1000"))
Set cell_range = Worksheets("Inventory").Range("A8")

' FYI, cell_count = 546 in my example

End Sub


Private Sub add_item_Click()

Dim cell_row As Long
Dim lastrow As Long

Call cell_setup
add_amount = cell_range.Offset(cell_count + 3, 1).Value

' insert row
Range(cell_range.Offset(cell_count + 2, 0)).Select

'Range("A1:D10").Select

ActiveCell.Offset(1).EntireRow.Insert _
Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove

End Sub