Conception Calculator
Estimate when you conceived from due date, ultrasound dating, or last period. Shows conception window and fertile days.
HEALTHEstimate when you conceived based on your due date, ultrasound dating, or last menstrual period. Shows the most likely conception date plus the fertile window when intercourse may have led to pregnancy.
For a 28-day cycle, ovulation falls on day 14 of the cycle; conception happens within 24 hours of ovulation. For other cycle lengths, ovulation = cycle_length - 14 days. From a due date, conception = due_date - 266 days. From an ultrasound, conception = scan_date - (gestational_age + 14 days). The conception window spans about 5 days because viable sperm can wait in the fallopian tubes.