EDD

Due Date Calculator

Enter the first day of your last menstrual period to calculate your estimated due date, plus your current week of pregnancy and how many days remain.

First day of your last menstrual period (LMP)

Your Estimated Due Date

—

💡 Your due date is an estimate based on a 40-week (280-day) pregnancy from your LMP. Only about 5% of babies arrive exactly on their due date — most come within 2 weeks before or after.

Frequently Asked Questions

How is my due date calculated?

Your estimated due date (EDD) is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period. This is called Naegele's Rule and has been the obstetric standard for over a century.

Can my due date change?

Yes. Your provider may adjust your EDD after an early ultrasound, which can more accurately measure fetal size and gestational age. An adjusted due date is very common, especially with irregular cycles.

What if my cycles are longer or shorter than 28 days?

This calculator assumes a standard 28-day cycle. If your cycles are consistently shorter or longer, your actual due date may differ. Your provider can adjust using ultrasound measurements.

Is this medical advice?

No — this tool is for informational purposes only. Always follow the guidance of your doctor or midwife for official pregnancy dating.