What is my conception date based on last menstrual period?

What is the most accurate way to determine date of conception? I'm always on time with my periods and it's with a 28 day cycle. My 1st day of last menstrual period was on July 11, 2008. When could the conception date be?|||You would've ovulated on the 25th, 14 days after your lmp. Conception should've occured somewhere close to that date.|||If your cycle is a normal 28 day cycle you are most likely to ovulate 13 to 15 days after the first day of your last period. Sperm can live up to 3 days. You most likely conceived the 24th to the 26th.|||Generally speaking, your conception date would be on day 14 of your cycle, so..... around July 25th.|||july 25 2008 around