Pregnancy Due Date Calculator
Estimate your due date, current pregnancy week, trimester and key milestones.
How to use the Pregnancy Due Date Calculator
- 1Choose your method: last period, conception date or IVF transfer.
- 2Enter the date, and your cycle length or the embryo age.
- 3Read your due date, how far along you are and the milestones ahead.
About Pregnancy Due Date Calculator
The Pregnancy Due Date Calculator estimates when your baby is due and how far along you are. Calculate from the first day of your last menstrual period with Naegele's rule (280 days), adjusted for your average cycle length from 20 to 45 days; from a known conception date (266 days); or from an IVF embryo transfer date, for a day-3 or day-5 (blastocyst) embryo.
Besides the due date, the calculator shows the current pregnancy week and day, the trimester, the approximate conception date and how many days are left, with a progress bar. A timeline lists the key milestones with their dates: a positive pregnancy test, the first heartbeat on ultrasound, first-trimester screening, the anatomy scan, glucose screening, the start of each trimester, full term and post-term. It is an estimate, not medical advice; your doctor or midwife may set a different date after an ultrasound.
Expecting parents use it to see how far along they are and to plan appointments, parental leave and the months ahead. If you are trying to conceive, the Ovulation Calculator estimates your fertile days.
Frequently asked questions
How is the due date calculated?
Naegele's rule adds 280 days, or 40 weeks, to the first day of the last menstrual period. For cycles longer or shorter than 28 days, the difference is added or subtracted. From a known conception date, the due date is 266 days later.
How is the due date calculated after IVF?
For a day-5 blastocyst transfer the due date is 261 days after the transfer; for a day-3 embryo it is 263 days. Both match a pregnancy dated from a period 280 days before the due date.
How many weeks pregnant am I?
Pregnancy weeks count from the first day of the last period, about two weeks before conception. If your last period started 10 weeks ago, you are 10 weeks pregnant even though the embryo is about 8 weeks old.
How accurate is a due date?
Only about 4 percent of babies are born on their due date. Most arrive between weeks 37 and 42, and an early ultrasound dates a pregnancy more precisely than the last period.
When do the trimesters start?
The first trimester runs to the end of week 13, the second from week 14 to the end of week 27, and the third from week 28 until birth.
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