Ovulation Calculator and Fertile Days Calendar

Estimate your ovulation day and most fertile days for the next six cycles from the first day of your last period and your usual cycle length.

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How to use the ovulation calculator

1. Type your numbers in the boxes (pick your currency or units if asked).
2. The answer updates as you type: no button to press.
3. Copy the result, or share it on WhatsApp with one tap.

Questions

When am I most fertile?

In the five days before ovulation and on the day itself. Ovulation is usually about 14 days before the next period starts.

Is my data private?

Yes. Everything happens inside your own browser: nothing you type or choose is uploaded to us or anyone else.

Is it free?

Completely free, with no sign-up, no watermark and no limit on how many times you use it. Light ads keep the site running.