This conception calculator tells you when you were conceived or in case of expectant mothers, when they conceived their baby. Discover below the form more on conception times and other facts related to the menstrual cycle.

Please choose whether you prefer to enter the birth date (due date)

Birth Date (due date): *

or the data of the menstrual cycle:

The first day of your last menstrual period: *

Menstrual cycle length: *

How does this conception calculator work?

This great tool can determine the probable conception date by using simple data from the menstrual cycle or just a simple birthday, depending on what you need to find out.

For instance if you are just wondering when you were conceived you can input your birthday and discover when is it likely that your biological parents had you.

Or if you are an expectant woman you can discover when you’ve conceived your baby based on the data of your menstrual cycle.

This conception calculator will only ask you to input the length of the menstrual cycle and the date of the first day of the last period in order to discover this date for you.

Example conception calculation and result

For instance, someone born on January 24th 1980 is likely to have been conceived around May 3rd 1979.

Or a pregnant woman with a cycle length of 30 days and first day of last period March 5th 2014 is likely to have conceived March 18th 2014.

The first result takes into account the length of a term pregnancy while the second result relies on the distance of 14 days between the first day of the period and the ovulation time when the baby could have been conceived.


This is also known as fertilization or fecundation and represents the moment of fusion between the male sperm and female egg. This process leads to the development of an embryo that during the pregnancy, after 38 weeks time will develop into a new born ready to be birth.

The date of conception depends on the female body menstrual cycle dates as the fusion between the egg and sperm can only take place when the egg is matured and released from the ovary and this only happens half way through the menstrual cycle at a date called ovulation date.

The conception date is a date in which a sexual intercourse takes place and it is situated at a range of a few days before and after the ovulation.


1) Wilcox AJ, Baird DD, Weinberg CR. (1999) Time of implantation of the Conceptus and loss of pregnancy. New England Journal of Medicine 340 (23):1796–1799

2) Marieb EN, Hoehn K. (2013) Human Anatomy and Physiology, 5th ed. Pearson

28 Dec, 2014