Conception Calculator

The conception calculator estimates possible fertilization dates in the next 3 months based on biological cycles. Enter your first day of LMP to calculate.





  • First day of Last Menstrual Period:  
  • Estimated conception date:  
  •   First day of menstrual period
  •   Estimated conception date

How to use the conception calculator

  • First Day of Last Menstrual Period - Enter the starting day of your last menstrual period
  • Average Length of Cycles - Default is 28 days, it may vary by people

The report generated inculdes an estimated conception date, and 3 months calendar with possible conception dates in the future, unless the calculating conception succeeds.

How is the conception date calculated

Here are some basic facts on the possibility of getting pregnant:

  • Ovulation occurs about midway through the menstrual cycle(approximately day 14 of a 28-day cycle)
  • After ovulation, the egg will be available to be fertilized by sperm
  • Sperm can live for 3 to 5 days in a woman's body
  • Fertile window—days most likely to conceive, lasts several days after ovulation

it is hard to know when the conception occurred, so conception date here is merely an estimate based on the first day of last period.