Due Date Calculator –

When will my baby be born?

As soon as the pregnancy is confirmed, one of the first questions that comes up is: When will my baby be born? We’ll calculate the estimated due date together—and confirm it early on via ultrasound. First things first: The due date is a guideline, not a fixed date on the calendar.

How the appointment due date is calculated

Counting from the first day of your last period, a pregnancy lasts about 40 weeks or 280 days. This gives us the estimated due date. If you know the date of conception—for example, after fertility treatment—we’ll calculate from there: It takes about 266 days from the day of conception.

If your cycle is regularly longer or shorter than 28 days, the appointment shifts accordingly: with a longer cycle, the baby will arrive a few days later; with a shorter cycle, a few days earlier.

Why the appointment date is only an estimate

As precise as the calculation may sound, nature doesn’t follow the calendar. Only about 3 out of 100 babies are actually born on the calculated due date. The vast majority (95%) are born within the two weeks before or after that date—that is, between the end of the 38th and the 42nd week. The due date is therefore a rough guide that you shouldn’t rely on down to the exact day—and there’s no need to worry if your baby takes a little longer.

We confirm the appointment with an ultrasound

Between the 7th and 12th weeks, we verify the appointment with an ultrasound exam. At this early stage, the baby’s gestational age can be determined very accurately based on its size—often more accurately than by the date of your last period, especially if you have an irregular cycle. If the appointment determined by ultrasound differs from the calculated one, the ultrasound result is generally considered the definitive appointment (more on this → “Ultrasound”).