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Period Calculator

Track your menstrual cycle and predict your next period. Calculate fertile window and ovulation dates.

Average: 28 days

Understanding Your Menstrual Cycle

The menstrual cycle has four phases, with day 1 being the first day of your period.

Cycle Phases

  • Menstruation (Days 1-5): Period bleeding
  • Follicular (Days 1-13): Egg develops in ovary
  • Ovulation (Day 14): Egg released
  • Luteal (Days 15-28): Uterus prepares for possible pregnancy

Fertile Window

You're most likely to conceive during the 6 days ending on ovulation day:

  • Sperm can survive up to 5 days
  • The egg lives 12-24 hours after ovulation
  • Peak fertility: 1-2 days before ovulation

When to Consult a Doctor

  • Cycles shorter than 21 days or longer than 35 days
  • Very heavy or prolonged bleeding
  • Severe pain during periods
  • Missed periods (not pregnant)
  • Irregular cycles after being regular

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Frequently Asked Questions

How long is a normal menstrual cycle?

A typical cycle is 21-35 days, with 28 days being average. Cycles can vary month to month.

When is the fertile window?

Typically days 10-17 of a 28-day cycle, with ovulation around day 14. Sperm can survive 5 days.

What is ovulation?

When an egg is released from the ovary. It occurs about 14 days before your next period starts.

Why track my cycle?

To predict periods, identify fertile days (for conception or prevention), and monitor reproductive health.