Pregnancy Conception Calculator
Calculate your conception window and estimated conception date from your pregnancy due date.
Pregnancy Conception Calculator
Enter your estimated due date to calculate when conception likely occurred
About Pregnancy Conception Dating
This calculator works backwards from your due date to estimate when conception occurred. Using the standard 280-day (40-week) pregnancy duration and typical ovulation timing, it calculates your most likely conception date and a realistic conception window.
•How Reverse Dating Works
- –Standard Pregnancy: 280 days (40 weeks) from first day of last period
- –Ovulation Timing: Typically occurs 14 days after period starts
- –Conception Window: Sperm can survive 5 days; egg survives 24 hours
- –Due Date Minus 266: Conception date = due date - 266 days
•Understanding the Conception Window
- –Fertile Window: 5 days before ovulation to 1 day after
- –Sperm Lifespan: Can survive up to 5 days in reproductive tract
- –Egg Lifespan: Only viable for about 12-24 hours after release
- –Best Chances: Intercourse 1-2 days before ovulation
•Pregnancy Trimesters
- –First Trimester: Weeks 1-13 (organ development, morning sickness)
- –Second Trimester: Weeks 14-27 (movement felt, anatomy scan)
- –Third Trimester: Weeks 28-40+ (rapid growth, preparation for birth)
- –Full Term: 37-42 weeks is considered normal delivery range
•Important Considerations
- –Estimation Only: This calculator provides estimates, not exact dates
- –Cycle Variations: Assumes typical 28-day cycle; yours may vary
- –Ultrasound Accuracy: Early ultrasound is most accurate dating method
- –Medical Guidance: Always consult healthcare provider for pregnancy care