đ¸ Ovulation Calculator
Estimate your ovulation day, fertile window and next period.
Results are estimates for information only and are not medical advice. See our disclaimer.
How to use the Ovulation Calculator
- Enter Last period start, Cycle length days.
- The result updates instantly as you type.
- Copy or note down your result.
How it works
Ovulation is about 14 days before the next period; the fertile window is roughly the 5 days before it plus the day after.
Example
Using the default values (Last period start: 2026-10-01, Cycle length days: 28):
Ovulation (approx.)Thu Oct 15 2026
Fertile windowOct 10 â Oct 16
Next periodThu Oct 29 2026
FAQ
Is the Ovulation Calculator free to use?
Yes. It is free, needs no signup and has no usage limits.
Is my data safe?
Yes. Everything is calculated in your browser, so what you type or upload is never sent to a server.
Can I use it on my phone?
Yes. KsWebProduction is built mobile-first and works in any modern browser.