How to Calculate Luteal Phase Length

A woman's fertility cycle consists of two distinct phases: the follicular phase and the luteal phase. The follicular phase occurs in the first half of the cycle between the onset of menses and ovulation. The luteal phase occurs in the second half of the cycle between ovulation and the onset of menses again. Most women have a luteal phase that spans a typical number of days each month. If you calculate luteal phase length, you can better understand your cycles and use this information to either achieve or avoid pregnancy.

Things You'll Need

• Calendar
• Basal thermometer

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Instructions

• 1

  Mark the calendar to note the date your period begins. Make a mark for each day your period continues and note the date your period ends.

• 2

  Watch for signs that ovulation has occurred. Some symptoms of ovulation may include light spotting that may last one day, slight ovarian pain, known as mittleschmerz, changes in your cervical fluid and a temperature spike.

• 3

  Mark the calendar to note the date ovulation occurred. This begins the luteal phase of the monthly cycle.

• 4

  Begin counting the days from the day of ovulation and continue counting until the next menstrual period begins. Do not count the day the next menstrual period begins in the luteal phase. For example, if ovulation occurs on July 12 and menstruation begins on July 26, begin counting the luteal phase on July 12 and stop counting on July 25 to calculate a 14-day luteal phase.