Luteal Phase Calculator

Calculates your luteal phase length for any of your menstrual cycles. To use, enter the date of ovulation and the first day of your next menstrual period.

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The luteal phase is the third and final phase of the menstrual cycle, following ovulation. Also referred as as days post ovulation (DPO), luteal length is the number of days between ovulation up to the day before the start of your next period. A normal luteal phase is considered to be between 10 and 16 days.

What's happening during the luteal phase: the corpus luteum (which forms from the follicle that released the egg at ovulation) produces progesterone primarily to maintain the thickness of the endometrium lining in the uterus in the event that fertilization occurs. In a nutshell (or, shall we say eggshell?!), our bodies prepare for the possibility of pregnancy by creating a nurturing environment onto which the fertilized egg can attach. But, if fertilization does not occur, the corpus luteum runs out of steam: progesterone production stops and the endometrium lining is shed via the process we all know and love - menstruation.

Disclaimer: This information is provided for educational purposes only. It is not intended as a substitute for advice provided by a medical doctor or qualified healthcare provider. You should not use this information for self-diagnosis or for treating a health problem or disease. If you have any questions whatsoever about your medical health or believe you have a medical problem or disease, you should contact your medical doctor or healthcare provider.