Cycle calculator

Period & Ovulation Calculator

Estimate your next period, ovulation day, fertile window, and pregnancy test date from your last period and cycle length.

Cycle prediction

Calculate your period and ovulation dates

Enter your last period date and cycle pattern to estimate your next period, ovulation day, fertile window, and pregnancy test date.

Results preview

Your cycle dates will appear here.

Submit the form to see your next period, ovulation day, fertile window, and pregnancy test date.

Understanding Your Menstrual Cycle & Ovulation

Tracking your menstrual cycle is key to understanding your overall reproductive health. Whether you are actively trying to conceive or simply want to plan ahead for your next cycle, our online Period & Ovulation Calculator provides clear, science-backed predictions based on your personal cycle history.

How Does the Ovulation Cycle Work?

According to the American College of Obstetricians and Gynecologists (ACOG), a typical menstrual cycle lasts between 21 and 35 days. Ovulation, the release of a mature egg from the ovary, usually occurs about 14 days before your next period begins.

Cycle PhaseApproximate TimingWhat Happens
Menstrual PhaseDays 1 - 5The shedding of the uterine lining (your period).
Follicular PhaseDays 1 - 13Your body prepares follicles to release an egg.
Ovulation DayAround Day 14 (in a 28-day cycle)The egg is released and is viable for 12 to 24 hours.
Luteal PhaseDays 15 - 28The body prepares for a potential pregnancy.

What is the Fertile Window?

Your fertile window is the timeframe in your cycle where pregnancy is possible. It spans 6 days in total: the 5 days leading up to ovulation, plus the day of ovulation itself. Sperm can survive inside the female reproductive tract for up to 5 days, which is why having intercourse in the days preceding ovulation significantly increases the chances of conception.

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Medical Disclaimer

This calculator provides estimates based on cycle averages. Cycles can vary because of stress, illness, postpartum changes, medication, hormonal conditions, or perimenopause. It is not a medical diagnosis or a substitute for professional reproductive health advice.