Ovulation Calculator
Predict your fertile window and ovulation day from your cycle.
Inputs explained
- Last Period Date — The first day of your most recent period.
- Cycle Length (days) — Days from one period start to the next. The average is 28.
How to use it
- Fill in the fields above — each input has a hint describing exactly what to enter
- Press Calculate to get your result instantly, right on this page
- Copy the result, save the tool to favorites, or share and embed it anywhere
Understanding the result
Example: With a Jan 1 start and 28-day cycle, ovulation is around Jan 15.
Frequently asked questions
Is the Ovulation Calculator free to use? Yes — it is completely free, with no sign-up, no download and no usage limits. You can use it as often as you need.
Is my data private? Yes. The calculation runs entirely in your browser — the values you enter are never sent to our servers, stored or shared with anyone.
What information do I need? Just the following: Last Period Date, Cycle Length (days). Each field includes a hint explaining exactly what to enter.
Can I use it on my phone? Yes — the tool is fully responsive and works on any device, and the same calculator is available in the EasyWorkCalcs mobile app.
Privacy
Everything you enter into the Ovulation Calculator is processed entirely in your browser. Nothing is uploaded, stored or shared — your data stays on your device.