Ovulation Calculator
Estimate your fertile window.
A general estimate assuming a regular cycle. Not a contraceptive method — cycles vary month to month.
About Ovulation Calculator
Ovulation Calculator is a free online tool that lets you estimate your fertile window — straight from your browser, with no software to install, no sign-up, and no watermarks. It runs on Windows, Mac, Linux, Android, and iOS, so you can use it on whatever device you happen to have to hand.
Enter your figures and Ovulation Calculator applies the right formula instantly, showing a clear breakdown so you understand how the result is reached — not just the final number. Adjust any input to compare scenarios side by side. Files and data are processed securely and removed automatically afterwards, and many steps run entirely on your own device for extra privacy. Because Ovulation Calculator is completely free and unlimited, you can use it as often as you need for work, study, or personal projects.
Benefits of Ovulation Calculator
Frequently asked questions
How does Ovulation Calculator work out the result?
Enter your values and Ovulation Calculator applies the relevant formula instantly, showing a clear breakdown alongside the final figure.
Can I compare different scenarios?
Yes — change any input and the result recalculates immediately, so you can weigh up options side by side.