I posted this the other day, but didnt get many responses..
My BF and I had an accident the other day.. According to an online ovulation calendar, it happened 3-4DPO. My question is.. How accurate is that? For someone who has regular 28 day periods would that mean the ovulation day would be pretty accurate too?
Nope. Every woman is different. There may be some on the 28 day cycle who ovulate on CD14 but highly unlikely. My cycles vary (well even more now since I am 5 months PP) but I would average 35-40 day cycles and ovulate on what ever day was 17 days before my period. So between CD 18 and CD23.
EDIT: On average a woman ovulates 14 days before her next period. But not always the case, like me for example. Some ovulate on their period, others right after. So the only way you would really know is if you track your cycle.
Most women ovulate 10 - 16 days before their next period. 14 days is pretty normal and I believe that is what a lot of applications use. For an individual woman, the time between ovulation and her period is usually about the same from month to month but if you aren't tracking your fertility signs, then you won't really know.
I really recommend reading Taking Charge of Your Fertility. It is a wonderful book and makes all of this a lot more clear .