Home
Back
Due Date Calculation:
| From: | To: |
The Due Date Calculator estimates the expected delivery date (EDD) based on the last menstrual period (LMP) using Naegele's rule. It provides a standard method for calculating pregnancy due dates used by healthcare professionals worldwide.
The calculator uses the standard obstetric formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The due date represents 40 weeks of gestation.
Details: Accurate due date calculation is essential for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.
Tips: Enter the first day of your last menstrual period in the date field. Ensure the date is accurate for the most reliable due date estimation. This calculator provides an estimate - always confirm with your healthcare provider.
Q1: How accurate is this due date calculation?
A: This method is accurate for women with regular 28-day cycles. Only about 5% of babies are born on their exact due date - most deliver within 2 weeks before or after.
Q2: What if my cycle is longer or shorter than 28 days?
A: For irregular cycles, ultrasound dating in early pregnancy is more accurate. Adjustments may be needed for cycles significantly different from 28 days.
Q3: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, which are most accurate in the first trimester.
Q4: Why is 280 days used instead of 9 months?
A: 280 days equals 40 weeks, which is the standard medical calculation. Calendar months vary in length, so weeks provide more consistent measurement.
Q5: When should I see a doctor after calculating my due date?
A: Schedule your first prenatal appointment as soon as you suspect pregnancy, typically around 8 weeks gestation for initial confirmation and dating.