ovulation calculator
estimate when you are likely to ovulate and your fertile window, based on your cycle length.
runs on your device · free · no sign-up
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frequently asked questions
how is ovulation estimated?
ovulation usually happens about 14 days before the next period, so ovulation day = cycle length − luteal phase (14 by default).
what is the fertile window?
the five days before ovulation and the day of ovulation, since sperm can survive several days.
can i use it for birth control?
no. these are estimates for regular cycles and not a contraceptive method or medical advice.