just for reference.
based on a typical (average) 28 day cycle.
based on the fact that sperm *can* survive for upto 5 days inside a fertile female.
day one is the first day of bleeding.
ovulation occurs around 14 days BEFORE a womans period.
this typically means around day 14 of her cycle.
therefore the sex most likely to get a woman pregnant occurs on the 5 days before and including ovulation - ie days 10 thru 14 inclusive.
Howwever, not all women have a 28 day cycle and even those that do - rarely have a "text book" cycle.
ovulation can occur early or late - you have no way of knowing, so always assume a female is fertile at any time.