Auto fill a range based on another cell

[Ricardo9211]

Hello all,
I am having a problem and need some assistance. I am auto filling a range of cells on O2 down with a formula and have it stoping all the way down at O12982, the problem i have is that my data can stop before or after that point depending on the report. so how can i say that it should auto fill as long as there is data in A column

 
Range("O2").Select
    ActiveCell.FormulaR1C1 = "=RC[-1]/60"
    Range("O2").Select
    Selection.AutoFill Destination:=Range("O2:O12982")
    Range("O2:O12982").Select

Thanks