Ovulation... I Dont know when my luteal phase is. I have a 27 days cycle.. READ ON?

I looked at some ovulation calendars and they all say something different. I just need to know cause if you dont know you cant pinpoint a time to have .. Plus how long does sperm say in a females body after .. Cause i had on the 30th and if it stays in for 72 hours it could still be in there doing my ovulation. thats what the calendar said.. just help on luteal phase and pinpointing it