Ovulation & Fertile Window Calculator
Estimate your ovulation day, fertile window and next three periods from your last period and cycle length.
About the Ovulation & Fertile Window Calculator
Ovulation usually happens about 14 days before the next period. The fertile window covers the five days before ovulation and the day after. Enter the first day of your last period and your average cycle length to see estimates for the next three cycles.
How to use the Ovulation & Fertile Window Calculator — step-by-step guide
Frequently asked questions
Is the Ovulation & Fertile Window Calculator free?
Yes. The Ovulation & Fertile Window Calculator on Apex Tool Station is 100% free with no signup and no watermark. Browser tools have no usage limits.
Are my files or data uploaded to a server?
No. Everything runs locally in your browser using JavaScript. Your files and text never leave your device, which makes it safe for private documents.
Does it work on mobile?
Yes. The tool works on any modern browser on Android, iPhone, Windows, Mac and Linux.