Ovulation Calculator

Estimates your ovulation date and fertile window from your last period.

Lilu Baba's Ovulation Calculator estimates your likely ovulation date and fertile window using standard luteal-phase timing. This is informational only, not medical advice — actual ovulation timing varies by individual.

First Day of Last Period

Average Cycle Length (days)

How to use this calculator

Enter the first day of your last period.
Enter your average cycle length.
Your estimated ovulation date and fertile window update instantly.

Estimated Ovulation Date —

Fertile Window Starts —

Fertile Window Ends —

FAQ

Ovulation Calculator — frequently asked questions

Typically around 14 days before your next expected period, regardless of cycle length (the luteal phase is fairly consistent at ~14 days).

Less accurate for irregular cycles — consider tracking basal body temperature or using ovulation test kits for more precise timing.