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Ovulation Calculator

Predict ovulation date and fertile window based on menstrual cycle.

Ovulation Calculator

Estimate your ovulation day and fertile window based on your last period and average cycle length.

First day of your last period

Average cycle length (days)

21–45

Luteal phase length (days)

10–16

Ovulation typically occurs about 14 days before your next period. The fertile window usually spans the five days before ovulation through the day after. Results are estimates and can vary from person to person. This tool is for informational purposes only and is not a substitute for medical advice.