Ovulation Calculator

Estimate your ovulation day, fertile window, and next period dates based on your menstrual cycle.

Estimated Ovulation Day
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Fertile Window
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Next Expected Period
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Best time to take a pregnancy test: -- DueDate if conceived: --

Upcoming Fertile Windows

About Ovulation & Fertility Tracking

The Ovulation Calculator estimates your most fertile days of the month by tracking your menstrual cycle dates.

How It Works

  • Luteal Phase Estimate: Ovulation typically occurs roughly 14 days before the start of your next menstrual period.
  • Fertile Window: Sperm can survive inside the female reproductive tract for up to 5 days, making the 5 days leading up to ovulation and the day of ovulation your prime conception window.

Note: This tool provides general calendar estimates and should not be used as a primary method of birth control.

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Handy web tools for daily use. Everything runs right in your browser—no sign-ups, no cloud uploads, and your data stays entirely on your device.