Ovulation Calculator
Calculate your estimated ovulation date and peak fertile window based on your last menstrual period (LMP) and cycle length. See your next 3 cycles at a glance — useful for conception planning and cycle tracking.
Complete User Guide
Enter the first day of your last menstrual period, your average cycle length (default 28 days), and luteal phase length (default 14 days). Get your ovulation date, fertile window, and next 3 cycle predictions.
The Mathematical Formula
Ovulation Day = Cycle Start + (Cycle Length − Luteal Phase Length)
Ovulation occurs approximately (Cycle Length − Luteal Phase) days after the first day of the last period. The fertile window spans 5 days before ovulation through 1 day after.
Frequently Asked Questions
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