Ovulation calculator: find your fertile window
Enter the first day of your last period and your usual cycle length. We'll estimate when you're likely to ovulate, your most fertile days, and when your next period is due.
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Your estimated dates
Your next three cycles
These dates are estimates based on the average timing of ovulation, about 14 days before your next period. Your body may not follow the calendar exactly, so ovulation predictor kits, cervical mucus changes and basal body temperature can help you confirm it. If your cycles are irregular, see tracking ovulation with irregular periods or tracking ovulation with PCOS.
Don't use this calculator as contraception. If you've been trying for 12 months (or 6 months if you're 35 or over), consider speaking with a doctor about fertility and hormone testing.
Nothing you enter here is saved or sent anywhere. This tool is for general information and isn't a substitute for medical advice.