Ovulation Calculator

Calculate your ovulation date and fertile window.

Calculator

First Day of Last Period

Average Cycle Length (days)

Luteal Phase Length (days)

Result

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Ovulation occurs ~14 days before the next period. The fertile window is 5 days before and 1 day after ovulation. Sperm survive up to 5 days in the reproductive tract. Cycle irregularity is common; consult a gynaecologist if cycles are very irregular.