How accurate is this?

The estimate is reliable if your cycle is regular to within a day or two. If your cycle varies a lot month to month, ovulation is also shifting, so use this as a guide.

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Ovulation Calculator

Estimate when you are most likely to ovulate based on your cycle length and last period, including the most fertile window.

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First day of last period

Cycle length (days)

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Frequently Asked Questions

How accurate is this?: The estimate is reliable if your cycle is regular to within a day or two. If your cycle varies a lot month to month, ovulation is also shifting, so use this as a guide.

Ovulation Calculator

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Frequently Asked Questions