Conception Date Calculator
When did you conceive? Enter your due date or current gestational age to estimate your probable conception date, fertile window, and ovulation date.
How the Conception Date Calculator Works
From Due Date
When you enter your due date, the calculator subtracts 266 days to estimate your conception date. A standard pregnancy is 280 days (40 weeks) from the last menstrual period, with ovulation and conception typically occurring 14 days after LMP, giving 266 days from conception to due date.
From Gestational Age
If you enter your current gestational age, the calculator first determines your estimated LMP by subtracting the gestational age from today's date. Then it adds 14 days to estimate the ovulation/conception date, since ovulation typically occurs two weeks after the start of the menstrual period.
The Fertile Window
The fertile window is calculated as 5 days before to 1 day after the estimated ovulation date. Sperm can survive in the female reproductive tract for up to 5 days, so intercourse on any of these days could have resulted in pregnancy.
Implantation
After fertilization, the embryo takes 6-12 days to travel down the fallopian tube and implant in the uterine wall. The calculator shows this estimated implantation window.
Frequently Asked Questions
How is the conception date calculated from a due date?▾
The conception date is estimated by subtracting 266 days (38 weeks) from your due date. This is because pregnancy is 280 days from the last menstrual period, and conception typically occurs about 14 days after that, leaving 266 days from conception to due date.
Can I know the exact day of conception?▾
It is generally not possible to determine the exact day of conception. Sperm can survive in the reproductive tract for up to 5 days, so conception could have occurred from intercourse on any day within the fertile window. The calculator provides a probable date based on estimated ovulation.
What is the fertile window?▾
The fertile window is the period during which intercourse can lead to pregnancy. It typically spans 5 days before ovulation and 1 day after. This is because sperm can survive up to 5 days, while the egg is viable for about 12-24 hours after ovulation.
Is the conception date the same as the ovulation date?▾
Not necessarily. Conception (fertilization) usually occurs on or near the day of ovulation, but since sperm can survive for several days, the intercourse that led to conception may have occurred days before ovulation. The calculator estimates ovulation as the probable conception date.
Medical Disclaimer
This calculator is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider for medical decisions regarding your pregnancy.