How to use the Ovulation Calculator
- Enter the first day of your last period
- Enter your average cycle length
- See fertile days and ovulation dates
About this tool
Predict your fertile window and ovulation dates for the next six cycles. Ovulation Calculator is part of ToolNest's collection of free health & fitness. It works instantly in your browser with no account and no installation.
Frequently asked questions
Is the Ovulation Calculator free to use?
Yes. Ovulation Calculator on ToolNest is completely free, with no sign-up, no watermark and no daily limits.
How accurate is the Ovulation Calculator?
Ovulation Calculator uses standard, widely accepted formulas and calculates instantly as you type. Results are for general information — for important medical decisions, please confirm with a qualified professional or your institution.
Is my data saved anywhere?
No. Everything you enter stays in your browser. Nothing is sent to or stored on our servers.
Does Ovulation Calculator work on mobile phones?
Yes. ToolNest works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux. There is nothing to install.