1. What is the Reverse Due Date Calculator?

The Reverse Due Date Calculator estimates the conception date based on a known due date. It works backward from the due date to determine when conception likely occurred.

2. How Does the Calculator Work?

The calculator uses the standard pregnancy duration:

Where:

• 266 days — Standard length of human pregnancy from conception to birth
• Due Date — Estimated date of delivery (EDD)

Explanation: This calculation assumes a typical 38-week (266-day) gestation period from conception to delivery.

3. Importance of Knowing Conception Date

Details: Knowing the conception date can help determine gestational age, establish paternity, and provide important information for prenatal care and development tracking.

4. Using the Calculator

Tips: Enter the estimated due date (typically provided by your healthcare provider) to calculate the most likely conception date. Remember this is an estimate - actual conception may have occurred a few days before or after.

5. Frequently Asked Questions (FAQ)

Q1: Why 266 days?
A: This represents the average 38-week gestation period from conception to birth (40 weeks from last menstrual period).

Q2: How accurate is this calculation?
A: It provides an estimate. Actual pregnancy duration can vary by ±2 weeks from the due date.

Q3: Does this work for IVF pregnancies?
A: For IVF, the exact conception date is known and should be used instead of this calculation.

Q4: What if I know my last menstrual period (LMP)?
A: Conception typically occurs about 14 days after the first day of LMP in a regular 28-day cycle.

Q5: Can this determine the exact day I conceived?
A: No, it provides an estimate. Sperm can live up to 5 days in the reproductive tract, so conception may have occurred several days after intercourse.