Ovulation Calculator

Ovulation sits ~14 days before the NEXT period — cycle length drives everything. Map the next three fertile windows.

First day of last period

Average cycle length

days

Enter the required values above to see your result.

How the Ovulation Calculator works

The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:

How does the Ovulation Calculator work?

Enter your numbers above and results update instantly using standard formulas, computed entirely on your device.

Is the Ovulation Calculator free to use?

Yes — completely free with no signup required, and it works on phones, tablets, and desktops.

Predict upcoming periods from cycle history: start dates, duration, and fertile-day markers.

Fitness & Health

Estimate which intercourse date likely conceived, given a due date or birth date.

Fitness & Health

Estimate when conception occurred from the due date or last menstrual period, including IVF transfer dates.

Fitness & Health