Ovulation Calculator

Enter your last period date and average cycle length to predict your next ovulation and fertile window. Save results to compare trends over time.

First Day of Last Period

Average Cycle Length (days)

Luteal Phase Length (days, optional)

Default is 14 days. Most women have a luteal phase of 12-16 days.

No saved calculations yet. Calculate and save to see your history here.

Calculate your exact fertile days for better timing and planning.

Record period dates and see your personal trends over time.

All data is stored in your browser's localStorage. We never see your cycle information.