🤰Pregnancy Due Date Calculator

About this tool

Choose the method — last menstrual period with your cycle length, a known conception date, or an IVF transfer (day-3 or day-5 embryo) — and the tool gives the estimated due date, how many weeks and days you are today, the trimester, and the usual dates for scans and full term. Nothing is stored or sent.

How due dates are estimated

The estimate is Naegele's rule, the method clinics use before a dating scan: pregnancy is counted as 280 days (40 weeks) from the first day of the last period, which assumes ovulation around day 14 of a 28-day cycle. Longer or shorter cycles shift ovulation, so the tool moves the date by the difference. A conception date is simply 14 days after the notional period start; an IVF transfer adds the embryo's age. The early ultrasound is more accurate than any of these and your care team will use it to set the date you plan around. Perspective on the number itself: only about 4–5% of babies arrive on the due date, and most come within two weeks either side; 'full term' spans 37 to 42 weeks. This is general information, not medical advice — talk to your midwife or doctor about your pregnancy. The date difference calculator counts days to any date, the calendar shows the weeks, and the caffeine calculator helps with the 200 mg pregnancy guidance.

Frequently asked questions