Pregnancy Due Date Calculator

What is a Pregnancy Due Date Calculator?

A pregnancy due date calculator estimates the expected date of delivery (EDD) based on the first day of your last menstrual period (LMP). Most pregnancies last about 40 weeks (280 days) from the LMP. Knowing your estimated due date helps you and your healthcare provider plan prenatal care, schedule check-ups and prepare for the arrival of your baby.

How to Use This Due Date Calculator

1. Select the first day of your last menstrual period (LMP) from the date picker.

2. Click "Calculate due date" to see your estimated delivery date.

3. The calculator also shows your approximate pregnancy age in weeks and days.

Naegele's Rule

This calculator uses Naegele's Rule, the standard method used by doctors worldwide. The rule states: Due Date = LMP + 280 days (40 weeks). This assumes a regular 28-day cycle with ovulation occurring on day 14. Pregnancy is divided into three trimesters: First trimester (weeks 1-12), Second trimester (weeks 13-26), and Third trimester (weeks 27-40).

Frequently Asked Questions

How accurate is the due date calculation?

Only about 5% of babies are born on their exact due date. Most deliveries occur within a window of two weeks before or after the estimated date. Factors like cycle irregularity, first-time pregnancy and individual variation can affect the actual delivery date. An ultrasound scan in the first trimester can provide a more accurate estimate.

What if my cycle is not 28 days?

Naegele's Rule assumes a standard 28-day cycle. If your cycle is longer or shorter, the actual due date may differ. For cycles longer than 28 days, the due date may be slightly later, and for shorter cycles, it may be earlier. Your doctor may adjust the date based on an early ultrasound.

Should I use this as medical advice?

No. This calculator provides a general estimate only and should not replace professional medical guidance. Always consult your obstetrician or gynaecologist for accurate pregnancy dating, prenatal care and delivery planning.