Pregnancy Due Date

What is a Pregnancy Due Date Calculator?

A pregnancy due date calculator estimates when your baby will be born based on your last menstrual period (LMP) or ultrasound date.

How to Use This Calculator

Enter the first day of your last menstrual period. The calculator estimates your due date using Naegele's rule.

Naegele's Rule

Due Date = First Day of LMP + 280 days (40 weeks)

Pregnancy Trimesters

• First: Weeks 1-12
• Second: Weeks 13-26
• Third: Weeks 27-40

Important Notes

Only about 5% of babies arrive on their due date. Most arrive within 2 weeks before or after.

FAQ

Can the due date change?
Yes, first trimester ultrasound often refines the due date.