Ovulation does not occur during your menstrual cycle. Because the sperm can live in the body from 3-5 days, pregnancy can occur from having intercourse DURING your period. Estimated ovulation occurs anyhwere between 11-21 days following your menstrual cycle, or 12-16 from when you expect your next cycle. However there is no one way to pin point ovulation. It generally differs from woman to woman. All the best.
Ovulation is calculated from first day of bleeding.