Fertility Calculator

Tracks periods and the most fertile days for the next 12 menstrual cycles.

The first day of your last menstrual period:
Menstrual cycle length:
Period length:
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

Woman’s health fertility indicators

Predicted ovulation and fertility window are the keywords in the vocabulary of women trying to conceive, as well as checking cervical mucus and charting basal body temperature.

The basics of the menstrual cycle changes must be understood in order to be able to plan the best days for conception for those wishing to become pregnant. A cycle starts with the menstrual bleeding that debuts the follicular phase during which one of the ovaries prepares an egg.

The egg ready to be fertilized is then released at ovulation. Several changes in cervical mucus occur days before ovulation, so that sperm viability is protected and sperm can move through the female reproductive tract to reach the egg whilst that is viable.

If fertilization occurs, then the embryo implants in the uterus wall and the luteal phase focuses on implantation (6 to 9 days after ovulation) rather than on preparing the uterine layers for shedding during period (if fertilization does not occur). Some spotting or implantation bleeding could occur at the time of expected period but this is not mandatory.

This fertility calculator helps you keep track of your periods and most fertile windows for the next 12 menstrual cycles.

The main factors that influence female fertility include:

■ Age – up to the age of 35 doctors recommend trying to conceive for 12 months before asking for tests, after 35 and 6 months of trying to conceive, one should undergo fertility tests;

■ Irregular menstrual cycles – too short, too long, irregular, absent or anovulatory cycles;

■ Hormonal changes – i.e. too little estrogen, too much prolactin;

■ Stress;

■ Smoking;

■ Overweight, obsesity;

■ Ovulation disorders or damage to reproductive system – PCOS, pelvic inflammatory disease, previous surgery, premature ovarian failure.


Young B. (2006) Wheater's Functional Histology: A Text and Colour Atlas (5th ed.) Elsevier Health Sciences.

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

Specialty: Obstetrics Gynecology

System: Reproductive

Article By: Denise Nedea

Published On: April 14, 2020

Last Checked: April 14, 2020

Next Review: April 14, 2025