Ovulation Calculator

Free ovulation calculator — updated for 2025. Accurate, instant, no sign-up needed.

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Find your fertile window & most likely ovulation date

First Day of Last Period

Average Cycle Length (days)

Luteal Phase (days)

Ovulation Date

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Fertile Window

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Next Period

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Understanding Your Fertile Window

Ovulation typically occurs ~14 days before your next period. Sperm can survive 3–5 days, so the fertile window spans about 6 days around ovulation.

⚠️ Estimates based on average cycles. Individual cycles vary. Consult a healthcare provider for family planning.