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Ovulation Calculator

Estimate ovulation date and fertile window from last period and cycle length.

Typical range 21–35 days.

Estimated ovulation
Fertile window
Next period (est.)

About the fertile window

Ovulation typically occurs about 14 days before the next period. The fertile window starts up to 5 days before ovulation and ends about one day after, due to sperm survival and the lifespan of the ovum.

Important: Do not use this tool for birth control. Cycle variability and health factors can shift ovulation. Consider ovulation testing and speak with a clinician if trying to conceive.

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