Pregnancy Due Date Calculator — Know Your Estimated Due Date

Congratulations on your pregnancy! One of the first questions every expecting parent asks is: when is my baby due? Our free due date calculator gives you an instant estimate.

How Due Dates Are Calculated

Naegele's Rule (Last Menstrual Period Method)

The most common method estimates your due date as 280 days (40 weeks) from the first day of your last menstrual period, assuming a standard 28-day cycle. If your cycle is shorter or longer, the calculation adjusts accordingly.

Conception Date Method

If you know your conception date, your due date is estimated at 266 days (38 weeks) from that date.

IVF Transfer Date Method

For IVF pregnancies, due date is calculated based on your embryo transfer date, accounting for the embryo's age at transfer.

Understanding Pregnancy Trimesters

TrimesterWeeksWhat Happens First1-13Early development, morning sickness is common Second14-27Often called the "golden period" — energy typically returns Third28-40+Final growth phase, body prepares for birth

How Accurate Is a Due Date Calculator?

It's important to set realistic expectations: only about 5% of babies are born exactly on their calculated due date. Most babies arrive within two weeks before or after the estimated date. Your due date is a helpful planning tool, not a guarantee.

Gestational Age vs Fetal Age

Doctors typically use "gestational age," counted from your last menstrual period. This is different from "fetal age," which is counted from conception — gestational age is usually about two weeks ahead of fetal age.

When to See a Doctor

Always confirm your due date with a healthcare provider, ideally through an early ultrasound, which tends to be more accurate than calculation methods alone, especially if your cycles are irregular.

Try It Free

Use our Pregnancy Due Date Calculator — calculate by last period, conception date, or IVF transfer date, completely free.