I just came across this from a pregnanacy book:

We need to split the women mentrual cycle into two period:
1st part is from the 1st day of period until ovulation:
The duration of first part of mentrual cycle varies from individual depending on a women normal cycle. Some have cycle of 28 days and some have 33-36 days.
2nd part starts from after ovulation until next mentrual:
This period is normally 12-14 days and it should not exceed 16 days

Hence in conclusion, the ovulation is always 12-14 days before next period.
In order to know when is the ovulation day (Since the eggs life span is only 24hours), one should know her own cycle and backward 12-14 days from the estimated* next menstrual.

The best is to use the OPK (Ovulation Prediction Kit) to confirmt the ovulation day.

Does anyone know where can we purchase the OPK in Malaysia? and what is the price range?

It's cost me RM88 for Clearblue 5-in-1 OPK kit. ..
Hope this thing works..
Thanks everyone..