Period Calculator
Predicts your next three periods and estimated fertile window from your cycle history.
How this calculator works
Next periods are projected by adding your average cycle length. Ovulation is estimated 14 days before the next period (the luteal phase is more constant than the follicular phase), with a fertile window of the five days before ovulation plus ovulation day.
For education only, not medical advice. Talk to a healthcare professional about results that concern you.
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