Pregnancy Calculator

Due dates are calculated by taking the first day of your last menstrual period (LMP), adding 280 days (40 weeks), and adjusting for your specific cycle length. If your cycle is 30 days, 2 days are added to the standard 280 days.

Only about 4% of babies are born on their exact estimated due date. However, 90% of women give birth within a 4-week window between 37 and 42 weeks of pregnancy, making the calculator an excellent guide for prenatal preparation.

For IVF pregnancies, due dates are precise because the exact transfer date and embryo age are known. For a Day 3 embryo transfer, add 263 days to the transfer date. For a Day 5 blastocyst transfer, add 261 days.

If your cycle varies significantly (e.g. 35 to 45 days), LMP calculations may be inaccurate. We recommend selecting the Ultrasound method or Conception date method for the highest accuracy.