Pregnancy Due Date Calculator

Calculate your due date and track pregnancy milestones

Calculate Due Date
Enter the first day of your last menstrual period (LMP)

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How to Calculate Your Pregnancy Due Date

Pregnancy due dates are typically calculated based on the first day of your last menstrual period (LMP). The standard calculation assumes a 28-day menstrual cycle with ovulation occurring on day 14.

Understanding the Calculation

A full-term pregnancy is considered 40 weeks (280 days) from the first day of your LMP. This is known as Naegele's rule, named after the German obstetrician who developed it.

The Three Trimesters

  • First Trimester (Weeks 1-12): Major organ development begins
  • Second Trimester (Weeks 13-26): Baby grows rapidly, movement felt
  • Third Trimester (Weeks 27-40): Final development and preparation for birth

Important Disclaimer

This calculator provides an estimate only. Only about 5% of babies are born on their exact due date. Your healthcare provider may adjust your due date based on ultrasound measurements. Always consult with your doctor or midwife for medical advice.

When to See a Doctor

Schedule your first prenatal appointment as soon as you know you're pregnant. Most healthcare providers recommend scheduling this visit around 8 weeks of pregnancy.