How it Works
1. Specify Due Date.
2. Subtract average gestation period.
3. Identify fertile window.
What is Reverse Conception Calculator?
Backtracks 266 days (38 weeks) from the Estimated Due Date (EDD) to pinpoint the ovulation and fertilization window.
Step-by-Step Guide
- 1 Specify
- Target due date.
- 2 Backtrack
- Minus 266 days.
- 3 Pinpoint
- Conception window.
Example
Input: Due Jan 1
Result: Conception ~April 10
FAQ
Is conception day exact?
Sperm can survive 5 days; fertilization happens within 24h of ovulation.
Differs from LMP?
Yes, LMP is ~2 weeks before conception.
Ultrasound accuracy?
Early ultrasound is the gold standard for dating.
IVF dating?
IVF uses exact transfer date, not LMP logic.
Leap years?
Algorithm accounts for 366-day years.
⚕️ Safety First: This calculator provides general health estimates. It does not replace a clinical assessment by a doctor.
Conclusion
Gestational math assumes a standard 28-day cycle. Biological variability means conception likely occurred within a 5-day window around this date.