The Human Fertility Calculator

The following can be a helpful resource to easily and quickly calculate an individual's expected key fertility dates based on the mean average of historical medical statistics relating to female menstruation, ovulation and hormonal cycles. Please note that the results obtained  from this fertility calculator may be specifically approximate to the individual and no guarantee as to the accuracy of these results is intended or implied. Please see the discussion on Luteal Phase below

Date of Last Menstrual Period :
 
(MM/DD/YYYY  format)

Average Length of Usual Menstrual Cycles:

(22 to 45...defaults to 28

Average Luteal Phase Length:
 
(9 to 16...defaults to 14)

Estimated Best Conception Date:

Estimated Due Date after Conception:

Estimated Fetal Age:

Most women have a luteal phase that lasts 10-14 days. With the normal average being 14 days. This is the time when the follicle bursts, and then turns into a corpus luteum, which secretes progesterone. In the luteal phase, estrogen is no longer the predominant hormone (as it was in the follicular phase); instead progesterone is predominant. Progesterone production occurs 7 to 8 days after the LH surge, at the approximate time of implantation if fertilization of the ovum has been successful and conception has occurred. The length of the luteal phase is generally 14 days for most women unless a pregnancy occurs. The only way to determine the exact luteal phase length for an individual's menstrual cycle is through hormone specific blood tests. Unless you are certain of your average Luteal phase length, use the default 14 days.

Phases of the Menstrual Cycle

Note: Because progesterone causes an elevation in basal body temperature, daily measurement of basal body temperature can be used to determine whether or not ovulation has occurred. Basal body temperatures cannot be used to predict ovulation, as the temperature rise does not occur until after ovulation, but can confirm that ovulation has occurred.