1. What is the Due Date Calculator?

The pregnancy due date calculator estimates the expected delivery date based on the first day of your last menstrual period (LMP). This method, called Naegele's rule, assumes a 28-day cycle with ovulation on day 14.

2. How Does the Calculator Work?

The calculator uses the standard pregnancy formula:

Where:

• LMP — First day of last menstrual period
• 280 days — Equivalent to 40 weeks gestation

Explanation: The calculation adds 280 days (40 weeks) to the first day of your last period. This accounts for the typical 2 weeks before conception plus 38 weeks of pregnancy.

3. Importance of Due Date Calculation

Details: Knowing your estimated due date helps track pregnancy progress, schedule prenatal tests, and prepare for delivery. Only about 5% of women deliver on their exact due date.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period. The calculator will show your estimated due date and current gestational age in weeks and days.

5. Frequently Asked Questions (FAQ)

Q1: What if my cycle isn't 28 days?
A: The calculation assumes a 28-day cycle. For irregular cycles, an ultrasound dating scan may be more accurate.

Q2: How accurate is this calculation?
A: It's a general estimate. Only about 5% of women deliver on their exact due date, with most delivering within 2 weeks before or after.

Q3: When should I get an ultrasound?
A: First-trimester ultrasounds (8-13 weeks) provide the most accurate dating. Later ultrasounds may need adjustment based on LMP.

Q4: What if I don't know my LMP?
A: If you don't know your LMP, an early ultrasound can estimate your due date based on fetal measurements.

Q5: Can the due date change?
A: Yes, healthcare providers may adjust your due date based on early ultrasound findings or if your cycles were irregular.