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🔄 Cycle Tracking

Menstrual Cycle Calculator

Track and predict your menstrual cycle phases — follicular, ovulation, luteal and menstruation. Based on your cycle length and last period date.

The first day of your most recent period
Days from start of one period to the next (21–45)
Days from ovulation to next period (typically 14)

Understanding Your Menstrual Cycle

The Four Phases of the Menstrual Cycle

The menstrual cycle has four distinct phases driven by hormonal changes:

  • Menstruation (Days 1–5): The uterine lining sheds. This is the start of your cycle.
  • Follicular Phase (Days 1–13): Follicle-stimulating hormone (FSH) causes eggs to mature in the ovaries.
  • Ovulation (Day 14): The mature egg is released from the ovary. This is the most fertile time.
  • Luteal Phase (Days 15–28): The uterine lining thickens to prepare for possible implantation.

Why Tracking Your Cycle Matters

  • For conception: Identify your fertile window to maximize chances of pregnancy.
  • For health: Irregular cycles may indicate underlying health conditions like PCOS or thyroid issues.
  • For planning: Predict when your period will start to manage symptoms and plan ahead.

💡 Clinical Insight: The average cycle length is 28 days, but cycles of 21–35 days are considered normal. Variations of up to 7 days between cycles are common.

References

  • ACOG. (2023). Menstrual Cycle: Basic Biology.
  • Mayo Clinic. (2024). Menstrual Cycle: What's Normal, What's Not.
  • NIH. (2023). Ovulation and the Menstrual Cycle.

Frequently Asked Questions

The four phases are: Menstruation (days 1–5, shedding of uterine lining), Follicular phase (days 1–13, egg matures), Ovulation (day 14, egg released), and Luteal phase (days 15–28, uterine lining thickens).

Day 1 is the first day of your period. Ovulation typically occurs 14 days before your next period starts. The follicular phase is from day 1 to ovulation, and the luteal phase is from ovulation to the day before your next period.

A normal cycle ranges from 21 to 35 days, with the average being 28 days. Variations of up to 7 days are considered normal.

In a 28-day cycle, ovulation occurs around day 14. The general rule is ovulation occurs 14 days before your next period starts.

The luteal phase is from ovulation to the start of your next period. It typically lasts 14 days, but can range from 10–16 days.

Pregnancy is very unlikely outside the fertile window because the egg survives only 12–24 hours and sperm can survive up to 5 days.

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