Pregnancy Due Calculator

Due Date Calculator

Calculate your baby's estimated due date using your last menstrual period, conception date, or IVF transfer date.

Pregnancy Due Date Calculator
Calculate your estimated due date using your preferred method

This is the most common method. Naegele's rule adds 280 days (40 weeks) to your LMP date.

How the Due Date Calculator Works

Our due date calculator uses three well-established medical methods to estimate when your baby will arrive. The most common method, based on your Last Menstrual Period (LMP), follows Naegele's rule which adds 280 days (40 weeks) to the first day of your last period. This is the same method most healthcare providers use during your first prenatal visit.

If you know your exact conception date, perhaps through ovulation tracking or fertility treatments, the conception method provides a more personalized estimate by adding 266 days (38 weeks). For IVF pregnancies, we account for the embryo's age at transfer — 261 days for a day-5 blastocyst transfer and 263 days for a day-3 transfer.

LMP + 280 days

Standard Naegele's rule. Assumes a 28-day cycle with ovulation on day 14.

Conception + 266 days

More accurate if you know your exact conception date. Does not rely on cycle assumptions.

IVF Transfer + 261/263

Most precise method. Adjusts for embryo age at transfer (day-3 or day-5).

Remember that your due date is an estimate, not a guarantee. Only about 5% of babies are born exactly on their due date. Most arrive within two weeks before or after the calculated date, which is considered completely normal. Your healthcare provider may adjust your due date based on ultrasound measurements, especially during the first trimester when dating is most accurate.

When to Contact Your Healthcare Provider

If you have confirmed your pregnancy with a home test, schedule your first prenatal appointment around 8 weeks gestation. Contact your provider sooner if you experience bleeding, severe cramping, or have a history of pregnancy complications. Early prenatal care is essential for a healthy pregnancy.