Pregnancy Due Date Calculator 🤰

About This Calculator

This calculator uses Naegele's Rule to estimate your due date based on the first day of your last menstrual period (LMP). It also adjusts for your specific cycle length.

What is a Pregnancy Due Date Calculator?

A Pregnancy Due Date Calculator estimates the expected delivery date (EDD) based on the first day of your last menstrual period (LMP) or conception date. While only about 5% of babies are born on their exact due date, this estimate helps healthcare providers schedule prenatal check-ups, tests, and monitor fetal development throughout the 40-week pregnancy.

Naegele's Rule

Due Date = LMP + 280 days (or LMP + 7 days - 3 months + 1 year)

Naegele's Rule, used by most healthcare providers, assumes a 28-day menstrual cycle with ovulation occurring on day 14. The due date is calculated as 280 days (40 weeks) from the first day of the last menstrual period. For conception-based calculation, add 266 days (38 weeks).

Frequently Asked Questions

Due date calculators provide an estimate — only about 5% of babies are born on their exact due date. Most babies are born within 1-2 weeks before or after the estimated date. An ultrasound in the first trimester gives the most accurate due date, within ±5 days.
A full-term pregnancy is 39-40 weeks. Early term is 37-38 weeks, late term is 41 weeks, and post-term is 42+ weeks. Most healthcare providers consider 37-42 weeks as the normal delivery window.
If your menstrual cycle is longer or shorter than 28 days, the due date shifts accordingly. For a 35-day cycle, add 7 extra days to the standard calculation. Many modern due date calculators, including ours, allow you to input your cycle length for a more accurate estimate.
First trimester: Weeks 1-12 (embryo development, morning sickness). Second trimester: Weeks 13-26 (baby movements begin, gender identifiable). Third trimester: Weeks 27-40 (rapid growth, preparation for birth).

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