Chances of getting pregnant 4 days after periods?

Very unlikely: Not very likely. But do a pregnancy test at time of next menstrual cycle. It also depends on how long your menstrual cycles are. For example if your menstrual flow is 7 days and you had intercourse 4 days later then you are close to the ideal time for conception. Ideal time for pregnancy is approximately 14 days after the first day of your menstrual cycle.