TTC Tools - Ovulation Calculator

Increase your chances of getting pregnant! Our Ovulation Calendar is designed to help you predict ovulation - your peak time for becoming pregnant - as well as calculate a pregnancy due date given successful conception.

Directions: Simply enter your first day of your last menstrual period - as well as the average length of your cycle. For more precise results, enter the average length of your luteal phase. Click Calculate to determine your approximate date for ovulation!

First Day of Last Menstrual Period: MM/DD/YYYY Format
Average Length of Cycles: 22 to 45
Average Luteal Phase* Length: 9 to 16 Days
Click Here to read more about your Luteal Phase
Estimated Ovulation:
Estimated Due Date:
Estimated Fetal Age:

Use our free ovulation calculator to determine an approximate date of ovulation. If you have irregular menstrual cycles, the calendar may be less accurate than for women with regular menstrual cycles. Other methods of charting fertility can be found below in our "natural methods" categories.

During every menstrual cycle, a woman's body experiences countless changes and hormonal fluctuations, from the thermal shift that takes place when you ovulate to changes in the texture of cervical mucus - and even changes in the position of the cervix. Your body knows what it's doing - and learning about your reproductive system will help you plan to "time sex" and increase your chances of conceiving.

Click any of the links below to read about all the different natural method and signs that will help you learn about your body, fertility, and the quickest path to pregnancy!

Natural Methods of Prediction Ovulation: Fertility Charting

Natural Methods of Prediction Ovulation: Fertility Charting

To increase the chances of becoming pregnant, TTC women use various natural methods to chart fertility and calculate when ovulation will take place. These natural methods include:

  • Ovulation Tests allow you to predict the date of your LH Surge.
  • Basal Body Temperature charting confirms ovulation has occurred.
  • Fertility-Charting allows you to predict ovulation based on calendar patterns, cervical mucus changes, and your thermal shift in resting (or basal) body temperature.

Definitions: The Luteal Phase

The Luteal Phase is the interval starting the day after ovulation takes place and runs through the remainder of your menstrual cycle to day one of your next cycle. The length of your LP - or luteal phase - will typically be between 11 and 16 days. The average is 14 days, and the default LP length for our ovulation calendar is 14 days. The luteal phase corresponds to days past ovulation - or "DPO".

At the start of the LP, a women's bbt (basal body temperature) will undergo a clear "thermal shift" - a marked rise in temperature that is caused by an increase in the hormone progesterone. The reason for this thermal shift is to create a warmer, fertile environment for the ovum. To read more, click on the link above that discussed bbt or fertility charting.


Ovulation Calculator

Format: 5/19/2019
Increase your chances of getting pregnant! Our Ovulation Calculator will help you predict when you ovulate - your prime time for becoming pregnant.

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By TTC veteran and mother of two, Elizabeth Andrews.