Ovulation & Fertile Window Calculator
Estimate your ovulation date and fertile window based on the first day of your last menstrual period (LMP).
How This Ovulation & Fertile Window Calculator Works
This ovulation calculator uses a simple and widely used method: it estimates your ovulation date as 14 days after the first day of your last menstrual period (LMP). Around this time, an egg is released from the ovary and can be fertilized, which makes these days especially important if you are trying to conceive.
The calculator also shows your fertile window, which includes the five days before ovulation plus the ovulation day itself. Sperm can survive in the reproductive tract for several days, so having intercourse during this window increases the chances of pregnancy. By knowing your estimated fertile days, you can plan more effectively.
All calculations happen instantly in your browser. No information is stored or sent to any server, making this tool fast, private, and easy to use alongside a pregnancy or due date calculator.
Frequently Asked Questions
How is ovulation calculated?
Ovulation is estimated as 14 days after the first day of your last menstrual period (LMP) for a typical 28-day cycle.
What is the fertile window?
The fertile window is the period when you are most likely to get pregnant. In this calculator, it includes the five days before ovulation plus the ovulation day itself.
Can this calculator guarantee pregnancy?
No. This tool provides an estimate based on average cycle patterns. Every body is different, and many factors affect fertility and conception.
Is my data stored?
No. Your LMP date is only used in your browser to show the result. Nothing is tracked, saved, or sent anywhere.