Ovulation Calculator
Estimate your ovulation day, fertile window and next period from your last period — simple, private and free.
Ovulation Day
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Fertile Window
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Next Period
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This is an estimate for information only — not medical advice, and not a contraception method. Cycles vary; confirm important decisions with your doctor.
How to use
- Enter the first day of your last period.
- Slide the cycle length to your usual cycle (21–35 days) and set period length.
- See your ovulation day, fertile window and next period instantly.