Ovulation Calculator

An ovulation calculator in its simplest form estimates ovulation based on your cycle length and your last menstrual period date. Although this estimate is not very accurate, it may be helpful as a starting point. For accurate estimation of your ovulation and your fertile days, please register for our free fertility tracker and apps.

Please enter the date of your last menstrual period and your usual cycle length and then click the Calculate button:

Ovulation Calculator
Last Menstrual Period:
Usual Cycle Length:


Ovulation Facts:
  • Ovulation occurs around cycle day 14 for an average cycle length of 28 days.
  • If your cycle length is longer or shorter than 28 days, ovulation may occur around 14 days before your next period.
  • Your cycle start day is the first day of full red flow.

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Disclaimer: This ovulation calculator is intended for educational purpose only. It is not accurate enough to be used for preventing pregnancy or any other purpose requiring accurate ovulation determination. Please consult your healthcare provider for any health related questions and issues.

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