Pregnancy Due Date Calculator

Calculate your estimated due date and pregnancy week.

First day of last menstrual period

Frequently Asked Questions

How is the due date calculated?

Using Naegele's rule: the due date is 280 days (40 weeks) after the first day of your last menstrual period (LMP), or 266 days (38 weeks) after conception.

How accurate is this calculator?

This calculator provides an estimate. Only about 5% of babies are born on their exact due date. Most births occur within two weeks before or after the estimated date.

What are the trimesters?

First trimester: weeks 1-12. Second trimester: weeks 13-27. Third trimester: weeks 28-40.