Ovulation Calculator
Find your most fertile days and ovulation date from your last period and cycle length.
How it works
Ovulation usually happens about 14 days before your next period. From your last period and cycle length, this tool estimates your ovulation day and your fertile window — the ~6 days when conception is most likely. It's an estimate, not a contraceptive method.
How it works
This tool estimates your most fertile days from the first day of your last period and your typical cycle length. Ovulation — when an ovary releases an egg — usually happens about 14 days before your next period starts, not 14 days after the last one. Because an egg survives around 24 hours and sperm can live up to about 5 days, your fertile window spans roughly the five days before ovulation plus the day itself. The calculator highlights this window so you can time trying to conceive, or simply understand your cycle. These are estimates based on a regular cycle. Stress, illness and natural variation shift ovulation, so treat the dates as a guide. For contraception or medical decisions, use a method validated by a healthcare professional.
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Frequently asked questions
When am I most fertile?
Your most fertile days are the day of ovulation and the 5 days before it — that's the fertile window this calculator shows.
Is this reliable for avoiding pregnancy?
No. It's an estimate based on average cycles and should not be used as a contraceptive method. Ovulation can vary from cycle to cycle.
When exactly do I ovulate?
Usually about 14 days before your next period. On a regular 28-day cycle that is around day 14, but it shifts with your cycle length.
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