Ovulation Calculator
Find your fertile window and best days to conceive based on your cycle.
How to use
- Enter the first day of your most recent period.
- Set your average cycle length — 28 days is the average but many women range from 21–35 days.
- Enter how many days your period typically lasts.
- Click Calculate to see your ovulation date and fertile window.
- Ovulation typically occurs 14 days before your next period starts.
- The fertile window is 5 days before ovulation plus ovulation day itself — sperm can survive up to 5 days.
- The 3-month chart shows upcoming cycles, fertile windows, and ovulation days.
About this Ovulation Calculator
Use this free ovulation calculator to estimate fertile windows and likely ovulation timing based on cycle details. It is useful for general planning, cycle tracking, and calendar estimates. No signup is required, and the tool works on phones, tablets, and desktop browsers.