Is Ovulation & Fertile Window Calculator free to use?

Yes, Ovulation & Fertile Window Calculator is completely free. No account, no sign-up, and no hidden fees required.

Does Ovulation & Fertile Window Calculator work offline?

Ovulation & Fertile Window Calculator runs entirely in your browser. Once the page is loaded, most features work without an internet connection.

Your data never leaves your device. All processing happens locally in your browser — nothing is uploaded to any server.

Health Tools

Calculate your ovulation date, fertile window, and next period based on your cycle length

1만 명 이상의 개발자가 사용

Your Cycle Details

First Day of Last Period (LMP)

Cycle Length (days)

Average: 28 days

Luteal Phase (days)

Ovulation: day 14

Fertile Window

Current phase based on your cycle

Key Dates — Current Cycle

Last Period StartedMar 19, 2026

Fertile WindowMar 28, 2026 – Apr 3, 2026

Ovulation DayApr 2, 2026

Next Period ExpectedApr 16, 2026

Next Fertile WindowApr 25, 2026 – May 1, 2026

Next OvulationApr 30, 2026

March 2026 Cycle Calendar

Sun

Mon

Tue

Wed

Thu

Fri

Sat

Period

Fertile

Ovulation

This tool is for educational purposes. Cycle predictions are estimates. Consult a healthcare provider for fertility planning.