Ovulation Calculator

This Ovulation Calculator helps you estimate your ovulation date and fertile window based on the first day of your last menstrual period and average cycle length.

Ovulation usually occurs about 14 days before the next period.

Ovulation & Fertility

Estimated Ovulation Date
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Fertile Window
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Next Expected Period
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What Is Ovulation?

Ovulation is the process in which an ovary releases an egg, typically occurring once during each menstrual cycle. The egg survives for about 12–24 hours after release.

What Is the Fertile Window?

The fertile window includes the five days before ovulation and the day of ovulation itself. This is the time when pregnancy is most likely to occur.

How Ovulation Is Calculated

Ovulation is generally estimated using this formula:

Ovulation Day = Cycle Length − 14

This calculator applies that estimate to your menstrual cycle to predict ovulation and fertility dates.

Signs of Ovulation

  • Changes in cervical mucus (clear and stretchy)
  • Mild lower abdominal pain (mittelschmerz)
  • Slight increase in basal body temperature
  • Increased libido

Why Track Ovulation?

  • Improve chances of conception
  • Plan or avoid pregnancy naturally
  • Understand menstrual cycle patterns
  • Support reproductive health awareness

Frequently Asked Questions

You are most fertile during the fertile window, which includes the 5 days before ovulation and the day of ovulation.
No. Ovulation typically occurs about 14 days before your next period, which means the day can vary depending on cycle length.
Ovulation calculators provide estimates. Stress, illness, and hormonal changes can affect ovulation timing.
Ovulation predictor kits can help confirm ovulation by detecting hormonal changes.