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Ovulation calculator
Get to know your cycle's rhythm a little better. Enter the first day of your last menstruation and your usual cycle length.
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Calculate. Understand. Plan.
These dates are estimates. Ovulation can vary each month; the calculator does not confirm pregnancy and is not used as a method of contraception.
What is ovulation?
Ovulation is the release of an egg cell from the ovary. It usually occurs approximately 14 days before the next menstruation, but this period varies from person to person and from month to month.
How are fertile days calculated?
The calculator adds the cycle length to the last menstrual period date and subtracts the duration of the luteal phase. The fertile window is the 5 days before ovulation and the day of ovulation. Considering that the egg can survive for approximately 12–24 hours, the next day is also shown on the calendar as an additional buffer day.
Ovulation = Last Menstruation + Cycle Length − Luteal Phase
What if the cycle is irregular?
The average cycle length only provides an approximate plan. LH ovulation tests in urine and cervical mucus observations can provide additional information. Basal body temperature rise, however, usually indicates ovulation afterwards. If your cycle varies a lot, talk to your doctor.
Frequently Asked Questions
Does the calculator accurately show ovulation?
No. Calendar calculation does not measure ovulation; it is an estimate based on previous dates. Even regular cycles can have variations. For personal assessment, consult a doctor and use appropriate ovulation tests for accuracy.
Is pregnancy possible during menstruation?
Yes. Sperm can survive for several days in suitable conditions, and early ovulation is possible. The days shown on the calendar do not mean safe protection days.
When should I take a pregnancy test?
Most home tests are more reliable from the first day of a missed period. If you don't know your next menstrual period date, test at least 21 days after unprotected intercourse. If the result is negative and the delay continues, repeat after a few days.
Are the dates I entered saved?
The website calculator processes dates only on this browser page. It does not create an account or health record. When you export to a calendar, you choose where to save the file yourself.
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