Fertile Window Calculator

Estimate your ovulation date, fertile window, and next expected period.

First Day of Last Period Average Cycle Length Select cycle length 21 days 22 days 23 days 24 days 25 days 26 days 27 days 28 days 29 days 30 days 31 days 32 days 33 days 34 days 35 days Period Length Optional

Your Estimated Result

Ovulation Date:

Fertile Window Starts:

Fertile Window Ends:

Most Fertile Days:

Next Expected Period:

What is a Fertile Window?

Your fertile window is the time in your menstrual cycle when pregnancy is most likely to happen. It usually includes the five days before ovulation, the ovulation day, and sometimes one day after ovulation.

How This Calculator Works

This calculator estimates ovulation by subtracting about 14 days from your next expected period. It then estimates your fertile window around that ovulation date.

Medical Disclaimer:

This tool gives an estimate only. Fertile windows can vary due to stress, illness, irregular periods, breastfeeding, hormonal changes, or medical conditions. It should not replace medical advice or be used as a guaranteed method of contraception or conception.