Note that you don't generally have to select something to work on it.
I'm just selecting for clarity.
This macro selects A to M from activecell row and down to last row.
Does not matter which column has activecell.
Sub rangefinder()
Dim rng As Range
Dim lRow As Long
Set rng = Range(ActiveCell, Cells(Rows.Count, 1).End(xlUp))
rng.Resize(, 13).Select
End Sub
This macro selects from activecell in Column A to M and down to lastrow.
Sub rangefinder22()
Dim lRow As Long
With ActiveSheet
lRow = .Range("A" & Rows.Count).End(xlUp).Row
.Range(ActiveCell.Address & ":M" & lRow).Select
End With
End Sub
Gord