How is my due date calculated?

The most common method is Naegele's rule. It calculates the due date by adding 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP).

How accurate is a due date calculator?

Only about 5% of babies are born on their exact due date. The calculator provides an estimate. An ultrasound in the first trimester is the most accurate way to confirm the date.

Pregnancy Due Date Calculator

Estimate your baby's arrival date based on your last period.

Estimated Due Date

Select Date

Pregnancy Progress 1st Trimester

Conception Due Date

Current Week

Days Remaining

Conception Date

End of 1st Tri

Understanding Your Pregnancy Timeline

How is the due date calculated?

Our calculator uses Naegele's rule, the standard method used by healthcare providers. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). It also adjusts for cycle lengths other than the standard 28 days.

What if I don't know my LMP?

If you are unsure of your last period date, an early ultrasound (dating scan) is the most accurate way to determine how far along you are and your estimated due date. This is usually done between 8 and 14 weeks of pregnancy.

What are the three trimesters?

First Trimester: Week 1 to Week 12. Second Trimester: Week 13 to Week 26. Third Trimester: Week 27 until birth. Each stage brings different developmental milestones for the baby.

Is the due date exact?

Only about 4% of babies are born on their exact due date. A normal pregnancy can last anywhere from 37 to 42 weeks. The due date is an estimate to help you and your doctor plan prenatal care.